Data Structures, Algorithms, & Applications in C++
Chapter 17, Exercise 5

No, the greedy algorithm no longer guarantees to provide change using the fewest number of coins. For example, suppose we want to provide 48 cents in change. The greedy algorithm will give out three 14 cent coins, one nickel, and one penny; for a total of five coins. An optimal algorithm will give out four 12 cent coins in change.