C programming

 I need help with an assignment that I am doing. I have finished question 1 (was about Triangle types and whether they were valid, depending on what the user inputed), but I am stuck on question 2 (which has two parts).
Note that part 'b' is pretty much program 'a' except with added 'dollars'
Also I did not know really what rint() was in question 2b, so I did not add it to the program.

question 2a is:
You are asked to write a simple program that will accept an integer value in the range of 5-95 and in increments of 5 at a time, representing the number of cents to give to a customer in their change. The program should calculate how many coins of each denomination and display this to the user. Valid coin values are 50, 20, 10 and 5. Your solution (program and algorithm) should be modular in nature. This requires the submission of a high-level algorithm and suitable decompositions of each step.