The way with opening a tourist account with an Iranian bank means that you will only get the official exchange rate, exchange rate on the street gets you nearly 15% more of Iranian money. All hotels have lockers or a safe for your money because they know of the situation.
I have just been in Iran for 23 days and had no problem with that. I just went to the legal but private exchange offices at Ferdowsi Street in Tehran and allways deposited my money with the reception of my hostels/hotels.
Regards, Marcus
MarcusBaumgartner is right. But, you can change your money on Fersowsi Street and then put in a bank account. For example, at Melli-ye Iran Bank (bmi.ir) and get a tourist card that works with all POS devices