Programming Challenge 4.12 - Software Sales

/* Software Sales - A software company sells a package that retails at $99. Quantity
   discounts are given according to the following table:
  
   Quantity                            Discount
   10-19                            20%
   20-49                            30%
   50-99                            40%
   100 or more                        50%

   This program asks for the number of units sold and computes the total cost of the
   purchase.

   * Input Validation: The number of units has to be greater than 0. */

#include "Utility.h"

int main()
{
    /* Hold constant for retail price */
    const float RETAIL_PRICE = 99.0;

    /* Hold sales, quantity and discount */
    float quantity,
        discount,
        sumTotal;

    /* Ask the user for the quantity sold */
    cout << "Enter the amount of units sold: ";
    cin >> quantity;

    /* Format the output */
    cout << fixed << showpoint << setprecision(2);

    if (quantity > 0 && quantity < 10)
    {
        sumTotal = (quantity * RETAIL_PRICE);
        cout << "Sum Total: $" << sumTotal << endl;
    }
    else if (quantity >= 10 && quantity <= 19)
    {
        discount = (quantity * RETAIL_PRICE) * .2;
        sumTotal = (quantity * RETAIL_PRICE) - discount;
        cout << "Sum Total: $" << sumTotal << endl;
    }
    else if (quantity >= 20 && quantity <= 49)
    {
        discount = (quantity * RETAIL_PRICE) * .3;
        sumTotal = (quantity * RETAIL_PRICE) - discount;
    }
    else if (quantity >= 50 && quantity <= 99)
    {
        discount = (quantity * RETAIL_PRICE) * .4;
        sumTotal = (quantity * RETAIL_PRICE) - discount;
        cout << "Sum Total: $" << sumTotal << endl;
    }
    else if (quantity >= 100)
    {
        discount = (quantity * RETAIL_PRICE) * .5;
        sumTotal = (quantity * RETAIL_PRICE) - discount;
        cout << "Sum Total: $" << sumTotal << endl;
    }
    else
    {
        cout << "The quantity must be greater than 0.\n";
    }

    pauseSystem();
    return 0;
}