In order to purchase goods, services or souvenirs in Tiraspol, or in any Transnistrian locale you must exchange your outside currency into Transnistrian rubles. The Transnistrian central bank sets their own exchange rate and prints their own money, so the amount of rubles you will get on any given day for your euros varies significantly from week to week. Currency exchanges are everywhere, including inside many popular stores, and will change most local and major currencies. Some exchange booths e.g. those of the Agroprom Bank which are located at the Sheriff stores will ask for your passport. You can't pay with credit or debit cards in Transnistria. Also be aware that there is only one ATM in Tiraspol, on 25th October street, from which you can withdraw only Russian Rubles or US dollars. These can be exchanged promptly at nearest exchange kiosk.
