The Cens is the standard unit of currency in Amestris and is available in both paper bills and varied metal coins. It can be inferred that the paper bills are worth more, similar to many real-life currencies. It is equal to about one Japanese Yen in the real world.
A long-distance call on a pay phone is shown to have costed 520 cens, and a cup of coffee has costed 100 cens. A set of high-quality automail was shown to cost 10 million cens.
The "10 Cens" Coin is a brown (presumably copper) coin, with a "10" stamped on one side, and possibly a leaf or star on the other side. The "100 Cens" coin is a silver (presumably nickel) coin, with "100" stamped on one side, and the argent dragon, symbol of amestris, stamped on the other. Given that the debt owed to Roy Mustang by Edward Elric was 520 cens and consisted of one large silver coin and two 10 Cens coins, It can be inferred that the large silver coin is worth 500 Cens. However, it appears identical to the 100 Cens coin. So either Edward was only holding 120 Cens, or the 500 Cens coin has a similar appearance (maybe different size) to the 100 Cens coin. The 10,000 Cens paper bill has a drawing of central command on the back of it.