The code for the Invoice application

import java.util.Scanner;

public class InvoiceApp
{
    public static void main(String[] args)
    {
        // welcome the user to the program
        System.out.println("Welcome to the Invoice Total Calculator");
        System.out.println();  // print a blank line

        // create a Scanner object named sc
        Scanner sc = new Scanner(System.in);

        // do calculations until choice isn't equal to "y" or "Y"
        String choice = "y";
        while (choice.equalsIgnoreCase("y"))
        {
            // get the invoice subtotal from the user
            System.out.print("Enter subtotal:   ");
            double subtotal = sc.nextDouble();

            // calculate the discount amount and total
            double discountPercent = 0.0;
            if (subtotal >= 200)
                discountPercent = .2;
            else if (subtotal >= 100)
                discountPercent = .1;
            else
                discountPercent = 0.0;
            double discountAmount = subtotal * discountPercent;
            double total = subtotal - discountAmount;

            // display the discount amount and total
            String message = "Discount percent: "
                           + discountPercent + "\n"
                           + "Discount amount:  "
                           + discountAmount + "\n"
                           + "Invoice total:    " + total + "\n";
            System.out.println(message);

            // see if the user wants to continue
            System.out.print("Continue? (y/n): ");
            choice = sc.next();
            System.out.println();
        }
    }
}