I am having a problem with getting this to work.
does anyone have any ideas?

here is the code:

Code:
import java.io.*;
import java.math.*;
import java.util.*;

public class CashRegisterTester 
{
    public static void main(String[] args) 
    {
        CashRegister register = new CashRegister();
        
        register.recordPurchase(0.75);
        register.recordPurchase(1.50);
        register.enterPayment(2,0,5,0,0);
        System.out.print("Change= ");
        System.out.println(register.giveChange());
    }

    public class CashRegister 
    {              
        public CashRegister() 
        {
            purchase = 0;
            payment = 0;
        }
        public void recordPurchase(double amount)
        {
            purchase = purchase + amount;
        }
        public void enterPayment(int dollars, int quarters, int dimes, int nickels, int pennies)
        {
            payment = dollars + quarters * QUARTER_VALUE + dimes * DIME_VALUE 
                       + nickels * NICKEL_VALUE + pennies * PENNY_VALUE;
        }
        public double giveChange()
        {
            double change = payment - purchase;
            purchase = 0;
            payment = 0;
            return change;
        }
        
        public static final double QUARTER_VALUE = 0.25;
        public static final double DIME_VALUE = 0.1;
        public static final double NICKEL_VALUE = 0.05;
        public static final double PENNY_VALUE = 0.01;
        
        private double purchase;
        private double payment;
    }
}
and the output:

run:
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - non-static variable this cannot be referenced from a static context
at CashRegisterTester.main(CashRegisterTester.java:13)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

Any help would be greatly appreciated.