As we wrote in a previous post, due to sanctions (at the time of our travel in 2015, but also early 2016), it was not possible to use a foreign debit or credit card in Iran. Mastercard, Visa, Amex et al do not get accepted, so cash is needed.
USD is the better option to take, though EUR also gets accepted. Once, when most money changers were closed in Tehran due to a holiday, we tried in a hotel. Staff wanted to help, but it took something like half an hour until they got convinced, that EUR notes do not have a different value depending on the country you were from.
The currency is called Iranian Riaal (IRR), 10,000 of which is worth almost 100 forints (Hungarian currency) or 1/3 dollars. See latest rates for 10,000 Riyals on XE.com.
Iranians rarely quote the price of anyting on Rials. They would say (or even write on a price tag) the value in “Toman”, i.e. 1/10th of the price in Rials. Here, e.g. the 10,000 Rials would be written as 1,000 Tomans.
Often in taxis but also elsewhere, they would count in 1,000 Tomans, i.e. just say one for 10,000 Rials, or five for 50,000 Rials. The five can also be said as “five thousand Tomans”.
enrouteiran.com 