Most of the currencies I can think of that are divided into cents / pence / whatever (British pound, Euro, Mexican dollar, Australian dollar, New Zealand dollar, South African rand, Latvian lat, Cypriot pound) have coins in the denominations 1, 2, 5, 10, 20, and 50.
All except US and Canadian cents, which are in the denominations of 1, 5, 10, 25 and 50.
Are these the only two countries in the world that use 25? Is there any particular reason why they use 25 instead of 20?
Are there any other "unusual’ denominations out there? Perhaps a 2 1/2 dollar bill? Or a 33 1/3 yen coin?