Do the taxis in Sao Paulo Brazil take US money or do they only accept their own currency?

From my travel experiences in Brazil (Rio and Sao Paulo) taxis and any other place only accept Reais, not dollars. I mean street taxis, the yellow and black cabs. However, once I took a taxi from my hotel (Sheraton Leblon) and the private driver accepted my dollars but this is very rare.

Real is the official currency in Brazil. USD or other currencies are not commonly used on the streets so accepting dollars would be up to the cab driver.

only the currency from the country or a credit card. watch out when you hand out your credit card because sometimes they might make a copy of your card number and use for something else. Worse comes you can always take money out of the ATM machines ans youll pay the rate exchange of that day

From my 6 years in Brazil, private drivers may take dollars, but the vast majority of the taxis take only reais. I'd advise getting some once you get there. It makes life a lot easier.

Plus foreign currencies are fun to look and and keep for later as souvenirs

Depends on the driver...some will accept US Dollar and Euro, and some only accept Brazilian Real.
Ask first.

No, US money is forbidden in Brazil (only Chinese and Bolivian smugglers use that).

The drivers only accept their own currency, Real (Reais), but at the airport you can prepay for your taxi with a credit card and if you do not arrive there too late (red eye flight) you can go to the exchange window for local currency.....

check out the current exchange rate at http://www.oanda.com/convert/classic

Brasil is a wonderful place to visit, not just for its beauty but for its people! Have fun!