The repetition structure: the while statement not working

[reync]

New programming student, have assignment as follows:
A restaurant has 4 lunch combos for customers to choose:

Combo A : Fried chicken with slaw [price: 4.25]
Combo B : roast beef with mashed potato [price: 5.75]
Combo C : Fish and chips [price:5.25]
Combo D : soup and salad [price: 3.75]

Write a program to calculate how much a party of customers should pay. Suppose the party orders 2 B’s, 1 A and 3 D’s. The casher will enter B, B, A, D, D, D and T into the program. The T means “calculating total of the order”. It is a signal telling the computer that the whole order has been entered and it is time to calculate the total amount the party should pay. Assume there is no sales tax. The following is an example:

Enter item ordered [A/B/C/D] or T to calculate total: B
Enter item ordered [A/B/C/D] or T to calculate total: B
Enter item ordered [A/B/C/D] or T to calculate total: A
Enter item ordered [A/B/C/D] or T to calculate total: D
Enter item ordered [A/B/C/D] or T to calculate total: D
Enter item ordered [A/B/C/D] or T to calculate total: D
Enter item ordered [A/B/C/D] or T to calculate total: T
Please pay this amount: 27

Have tried this example and something longer also. Cannot get the program to give any output after entering initial "combo" choice {A/B/C/D/T]. Must use "while" in this assignment. Book is no help, niether is my friend. What am I missing? below is my code so far:

// Lab08P3.cpp - Calculate and display how much a party of
// restaurant customers should pay for different combos.
// Created on 10/18/09

#include <iostream>

using std::cout;
using std::cin;
using std::endl;

int main( )
{
double cost = 0.0;
double costa = 0.0;
double costb = 0.0;
double costc = 0.0;
double costd = 0.0;
double costt = 0.0;
char answer = ' ';
char wouldorder = ' ';


cout <<"Would you like to order? ";
cin >>wouldorder;
wouldorder =toupper (wouldorder);


cout <<"Please enter your choice of combo's letter [A/B/C/D] from the list below:" <<endl;
cout << " Combo A : Fried chicken with slaw [price: 4.25]" << endl;
cout << " Combo B : Roast beef with mashed potato [price: 5.75]" << endl;
cout << " Combo C : Fish and chips [price:5.25]" << endl;
cout << " Combo D : Soup and salad [price: 3.75]" << endl<<endl;
while (wouldorder == 'Y')
{
cout << " Enter item ordered [A/B/C/D] or T to calculate total: ";
cin >> answer;
answer = toupper(answer);

while (answer == 'A')
{costa = 4.75;}
while (answer == 'B')
{costb = 5.75;}
while (answer == 'C')
{costc = 5.25;}
while (answer == 'D')
{costd = 5.75;}


while (answer == 'T')
{ costt = costa + costb + costc + costd;
cout <<"Your Total bill comes to: " << costt <<endl;
}
}
system("pause");
return 0;
}
Thanks in advance for the help. reync.

[screw]

#include <iostream>
#include <ctype.h>

using std::cout;
using std::cin;
using std::endl;

int main( )
{
//double cost = 0.0;	
double costa = 4.25;
double costb = 5.75;
double costc = 5.25;
double costd = 3.75;
double costt = 0.0;
char answer = ' ';
char wouldorder = ' ';


cout <<"Would you like to order? ";
cin >>wouldorder;
wouldorder =toupper (wouldorder);


cout <<"Please enter your choice of combo's letter [A/B/C/D] from the list below:" <<endl;
cout << " Combo A : Fried chicken with slaw [price: 4.25]" << endl;
cout << " Combo B : Roast beef with mashed potato [price: 5.75]" << endl;
cout << " Combo C : Fish and chips [price:5.25]" << endl;
cout << " Combo D : Soup and salad [price: 3.75]" << endl<<endl;
while (wouldorder == 'Y')
{
cout << "	Enter item ordered [A/B/C/D] or T to calculate total: ";
cin >> answer;
answer = toupper(answer);

switch (answer)
{
	case 'A': costt = costt + costa; break;
	case 'B': costt += costb; break; // it maches costt = costt + costb;
	case 'C': costt += costc; break;
	case 'D': costt += costd; break;
	default:
		wouldorder = 'N';
}
}
cout <<"Your Total bill comes to: " << costt <<endl;

system("pause");
return 0;
}

This while loop is endless if the answer is 'A' because the condition always true and repeat the assignment instruction again and again...

while (answer == 'A')
{costa = 4.75;}

This code is unnecessary.

while (answer == 'T')
{	costt = costa + costb + costc + costd;