Thread: [Homework] Calculating Change

The idea of this assignment is to simulate a customer buying goods from a store. The problem that I am having is that when I try and calculate how much change the customer should receive, my program treats $20.99 as $20 so when I try and convert the double into an integer it gives me 900 instead of 901. I have been working at this for a couple hours now and just can't seem to find where my error lies. Any suggestions or pointers to the right direction and I would be grateful.

I haven't finished my if statement or PrintWriter statements because I know my arithmetic is not working the way I want and need it to.

Here is my code:

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
 
 
public class store {
 
	/**
	 * @throws FileNotFoundException 
	 * @name	
	 * @purpose	Calculate purchases
	 * @date	February 6th, 2013
	 */
	public static void main(String[] args) throws FileNotFoundException 
	{
		Scanner Keyboard = new Scanner(System.in);
		PrintWriter prw = new PrintWriter("outputPA3.txt");
 
		double Beer = 1.95;
		double Chips = 1.79;
		double Coke = 3.99;
 
		System.out.println("Please enter your name:");
		String name = Keyboard.nextLine();
		System.out.println("Welcome to Stop and Rob, " + name + "! Today we have the following items on sale: ");
		System.out.println("Beer: $" + Beer);
		System.out.println("Chips: $" + Chips);
		System.out.println("Coke: $" + Coke);
		System.out.println();
		System.out.println("Please place your order:");
		System.out.println();
		System.out.println("How many beers would you like today?");
		int numBeer = Keyboard.nextInt();
		System.out.println(numBeer + " beers");
		System.out.println("How many bags of chips? ");
		int numChips = Keyboard.nextInt();
		System.out.println(numChips + " bags of chips");
		System.out.println("How many 12-packs of Coke would you like? ");
		int numCoke = Keyboard.nextInt();
		System.out.println(numCoke + " packs of Coke");
 
		double total = (Beer * numBeer) + (Chips * numChips) + (Coke * numCoke);
		System.out.printf("Your bill today is $%4.2f", total);
 
		System.out.println();
		System.out.println(name + " enter the amount you will be paying: ");
		double payment = Keyboard.nextDouble();
		System.out.println("The amount you entered is: $" + payment);
 
		if (payment >= total)
		{	
			int rAmount = (int)((payment - total) * 100);
			int rFives = rAmount / 500;
			rAmount = rAmount % 500;
			int rDollars = rAmount / 100;
			rAmount = rAmount % 100;
			int rQuarters = rAmount / 25;
			rAmount = rAmount % 25;
			int rDimes = rAmount / 10;
			rAmount = rAmount % 10;
			int rNickels = rAmount / 5;
			rAmount = rAmount % 5;
			int rPennies = rAmount;
			System.out.println("Your change of " + rAmount + " consists of \n" +
					"\t" + rFives + " fives\n" +
					"\t" + rDollars + " dollars\n" +
					"\t" + rQuarters + " quarters\n" +
					"\t" + rDimes + " dimes\n" +
					"\t" + rNickels + " nickels\n" +
					"\t" + rPennies + " pennies\n");
		}
 
	}
}