US Dollars are accepted almost everywhere in Tanzania. There is no need to exchange your US Dollars into Tanzanian Shillings while in Tanzania.
Most merchants will round up to the nearest dollar when doing a currency conversion so you may experience less buying power using US cash. For example, if a bottle of water is 1700 shillings and the current conversion is 1900 shillings to one US dollar. They will charge you one full dollar for the bottle of water.
Please note that your US dollars must be dated at least 2006 or newer. Many merchants will not accept US cash that is older than 2006. You can find out the date of your dollars by looking for the Series date on each bill.
ATMs are not very plentiful in Tanzania so we suggest that you bring all the cash that you think you may need. Do not rely on being able to find an ATM while you are in Tanzania.
Large hotels and restaurants will take credit cards. However, many will impose a fee of up to 5% for using a credit card. Smaller merchants and street vendors do not accept credit cards.