wrong accumulated service Charge in banking system

[wndtjr2]

I just made a program for banking account
But When i put initial balance let say $500 and put a "1" code to withdraw
and finally put amount of money i want to withdraw from the balance.
But ServiceCharge has to be accumulated in the CheckingAccount class but
It seems they are not accumulated in the class.
I think i made wrong loop structure but not sure what it is.

import javax.swing.JOptionPane;


public class BankAccount {

	static CheckingAccount check;
	static String input;
	static double initialBalance;
	static double transAmount;
	static double serviceCharge;
	static double currentBalance;
	static double toServiceCharge;
	static private double below500Charge = 5.00;
	static private double below0Charge = 10.00;
	static private double checkCharge = 0.15;
	static private double depositCharge = 0.10;
	static int transCode;
	
	public static void main(String[] args) {
		
		
		initialBalance = getInitialBalance(); // get initial balance
		check = new CheckingAccount(); // create CheckAccount class
		check.setBalance(initialBalance); // pass initial balance to CheckAccount class
		transCode = getTransCode(); // get trans code
		check.setTransCode(transCode); // pass trans code to CheckingAccount class
		
		//iteration until terminate the program
		
		while(transCode == 1 || transCode == 2){ // iteration as long as trans code is 1 or 2
			
			if(transCode == 1){
				transAmount = getTransAmount(); // get trans amount
				check.setTransAmount(transAmount); // pass trans amount to CheckingAccount class
				processChecking(); // display result of transaction
				transCode = getTransCode(); // get trans code again to iterate the loop
				check.setTransCode(transCode);// pass trans code to CheckingAcount class
			}
			else
				processDeposit();
		}
			processEnding();
		
	}

	public static double getInitialBalance() {
		
		double balance;
		input = JOptionPane.showInputDialog("Enter your initial balance: ");
		balance = Double.parseDouble(input);
		
		return balance;
	}
	

	public static int getTransCode() {
		
		int trCode;
		input = JOptionPane.showInputDialog("Enter the trans code: ");
		trCode = Integer.parseInt(input);
		
		return trCode;
	}
	
	public static double getTransAmount(){
		
		double tAmount;
		input = JOptionPane.showInputDialog("Enter the trans amount: ");
		tAmount = Double.parseDouble(input);
		
		return tAmount;
	}
	

	public static void processChecking() {
		
		// charge $ 5 only once when balance is below $ 500 
		
		currentBalance = check.getBalance();
		serviceCharge = check.getServiceCharge();
		transAmount = check.getTranAmount();
		if(currentBalance < 500){
				serviceCharge = below500Charge;
				check.setServiceCharge(serviceCharge); //pass service charge to CheckingAccount class
			if(currentBalance < 0){ // if balance is less than $ 0
				serviceCharge += checkCharge; // when account was withdrew, service fee charged by $ 0.15
				serviceCharge += below0Charge; // when account balance is below $ 0, service fee charged by $10
				check.setServiceCharge(serviceCharge); // pass to CheckingAccount class
				JOptionPane.showMessageDialog(null, "Transaction : Check in Amount of $" + transAmount +
						"\nCurrent Balance : $ " + currentBalance +
						"\nService Charge : Check --- charge $ " + checkCharge +
						"\nWarning balance below $ 50" +
						"\nService Charge : Below $ 0 --- charge $ " + below0Charge +
						"\nTotal ServiceCharge : $ " + serviceCharge);
			}
			else if(currentBalance < 50){
				serviceCharge += checkCharge;
				check.setServiceCharge(serviceCharge);
				JOptionPane.showMessageDialog(null, "Transaction : Check in Amount of $" + transAmount +
						"\nCurrent Balance : $ " + currentBalance +
						"\nService Charge : Check --- charge $ " + checkCharge +
						"\nWarning balance below $ 50" +
						"\nTotal ServiceCharge : $ " + serviceCharge);
			}
			else if(currentBalance < 500){
				serviceCharge += checkCharge;
				check.setServiceCharge(serviceCharge);
				JOptionPane.showMessageDialog(null, "Transaction : Check in Amount of $" + transAmount +
						"\nCurrent Balance : $ " + currentBalance +
						"\nService Charge : Check --- charge $ " + checkCharge +
						"\nTotal ServiceCharge : $ " + serviceCharge);
			}	
		}
		else{
			serviceCharge += checkCharge;
		check.setServiceCharge(serviceCharge);
		JOptionPane.showMessageDialog(null, "Transaction : Check in Amount of $" + transAmount +
				"\nCurrent Balance : $ " + currentBalance +
				"\nService Charge : Check --- charge $ " + checkCharge +
				"\nTotal ServiceCharge : $ " + serviceCharge);
		}
	}


	public static void processDeposit() {
		
	}


	public static void processEnding() {
		
	}


}

public class CheckingAccount {
	
	double balance;
	double transCode;
	double transAmount;
	double totalServiceCharge;
	double serviceCharge;
	
	public void setBalance(double bal){
		balance = bal;
	}
	
	public void setTransCode(int tCode){
		transCode = tCode;
	}
	public void setTransAmount(double tAmount){
		transAmount = tAmount;
	}
	
	public void setServiceCharge(double sCharge){
		totalServiceCharge = sCharge;
	}
	
	public double getTransCode(){
		return transCode;
	}
	
	public double getTranAmount(){
		return transAmount;
	}
	
	public double getBalance(){
		
		if(transCode == 1)
			balance = balance - transAmount;
		else if(transCode == 2)
			balance = balance + transAmount;
		return balance;
	}
	
	public double getServiceCharge(){
		return totalServiceCharge += totalServiceCharge;
	}	
}

[Junky]

public void setServiceCharge(double sCharge){
    totalServiceCharge = sCharge;
}

If you want the service charge to accumulate then I imagine some sort of addition would need to be performed.