I can't figure out why the mathematical calculations are not working
in this program.  It should be taking the duracion (number of days)
times the cost of the unit.  This is for a university class and I
could really use the help....  please!

import java.util.Scanner;

public class Prob2DOS
{

    public static void main (String[] args)
    {

        String titlePage = "\tWelcome to Yellowstone National " +
                "Park's Lodging Reservation System.\n\n" +
                "To complete your reservation, pleae answer the following
questions.\n" +
                "(After each entry, press the ENTER key.  Enter only one value per
question.\n\n";

        Scanner dosInput = new Scanner(System.in);

        //Declaring Variables
        String customerNameString;
        String customerUnitString;
        String customerDateString;
        int customerDate = 99/99/9999;
        String customerDuracionString;
        int customerDuracion = 9;
        String customerCostString;
        double customerCost = 999;
        String customerTotalString = "";
        double customerTotal;
        String continueString = "y";

        //Produce the title information
        System.out.println("\t\t\tYellowstone National Park Lodging
Reservation System" +
        "\n\t\tThis program produced by:   Mara Francis\n");
    while (continueString.equalsIgnoreCase("y"))
    {
        //Prompt and get input from User
        System.out.print("Your Name?");
            customerNameString = dosInput.next();
        System.out.print("Which unit do you wish to reserve?");
            customerUnitString = dosInput.next();
        System.out.print("Arrival date (format: MM/DD/YYYY)?");
            customerDateString = dosInput.next();
        System.out.print("What is the duracion of your stay?");
            customerDuracionString = dosInput.next();
        System.out.print("What is the cost of per-night rental?");
            customerCostString = dosInput.next();

        //Conversions
        customerCost = Double.parseDouble(customerCostString);

        //Calculations
        customerTotal = Math.round(customerCost * customerDuracion);

        //Output
        System.out.print("\nReservation for " + customerNameString + "\nYou
have reserved " + customerUnitString + " for "
        + customerDuracionString + " beginning on " + customerDateString +
".");

        System.out.print("\nYour total cost is: $" + customerTotal);

        System.out.print("\nYour price is based on a per night rental of $"
+ customerCostString);

        System.out.print("\nDo you wish to enter more data? (Y/N)");
            continueString = dosInput.next();

        }
    }
}