It would probably be easier to use switch/case in this situation. How about something like this?

Code:
#include <iostream>
#include <string>
#include <cctype>

using namespace std;

int main () {
	string s;

	do {
		cout << "What would you like today?" << endl;
		cin >> s;

		switch(toupper(s[0])){
		case 'W': 
			cout << "What is the amount?" << endl;
			//etc
			break;
		case 'Q': 
			cout << "Goodbye";
			return 0;
		default: 
			cout << "Invalid selection. Please try again." << endl;
			break;
		};
	}
		while(cin);

		return 0;
}