Write a program that computes and displays a 15 percent tip when the

Your question wasn't very clear, but I think I understand what you want. Additionally, you should really state what language you're working with. Here it is in C#, and shouldn't be too much of a hassle to translate in to other languages.

Console. Write ("Enter payment: ");

float payment;

if (float. TryParse (Console. ReadLine (), out payment))

Console. WriteLine ((Math. Floor (payment * 100) / 100) * 0.15, + " at 15% tip.");

else

Console. WriteLine ("Invalid input.");