dime: 5 cents
nickel: 10 cents
quarter: 25 cents
let's start with quarters, (2)
25 + 10 + 5
25 + 5 + 5 + 5
nickels, (4)
10 + 10 + 10 + 10
10 + 10 + 10 + 5 + 5
10 + 10 + 5 + 5 + 5 + 5
10 + 5 + 5 + 5 + 5 + 5 + 5
dimes, (1)
5 + 5 + 5 + 5 + 5 + 5 + 5 + 5
7 combinations.
hope it helps :)