Like elsewhere in Russia, the Russian rouble is the only currency officially accepted in the city.
Russian rouble (Russian: рубль [ˈro͞obəl], sign: ₽, руб; code: RUB).
The ruble is subdivided into 100 kopeks (kopecks or copecks; Russian: копе́йка [koˈpyeyka]).
Money exchange is not a problem, but use only official counters at banks and avoid people offering you exchange at major transport hubs. By Russian law, a passport is needed for exchange operations.
The approximate exchange rate was €1 = RUB75 or USD1 = RUB66 (Nov 2018).
Perm has many ATMs ("bankomat" in Russian), especially in the hotels and shops. You may withdraw not only roubles, but also US dollars or euro at some of them (approximately 10% of all ATMs).
Take into account, that Visa and MasterCard are widespread in Russia, but American Express cards are usually not accepted even at major tourist places. Also, expect possible problems with paying by card at minor shops or restaurants and at small private hotels. Have some cash with you for such cases.