Iran official currency is Rial while commonly Toman is used. Each 10 rials is equal to 1 toman and actually they are not different. Photos of Some of the banknotes in Iran are at the following
Exchange rate is not fixed and is highly recommended to exchange money at exchange offices. If you are from a country, cash of which is not common, it is better to change your money to dollars or euros. Internationally credit cards such as master or visa card are accepted only at some exchange offices and carpet shops.
Tipping is being more and more common these days.