The Change Will Do You Good Puzzle

Sugary Sue runs a small shop which sells sweets which run in price from 1p to £1 with every value in between. One day Hungry Horace came in to spend some of his £1 pocket money.

What is the smallest number of coins that Sue needs to set aside to guarantee having exactly the right change for whatever Horace will buy?

Type of coin available: 1p, 2p, 5p, 10p, 20p, 50p
Sue needs to be able to make any amount between 1p and 99p.