They may.... do you speak any Spanish..? You may need to be able to communicate to make sure you agree on an exchange rate for your Dollars. Not saying its impossible, but there are better options... like get a little Pesos from an ATM and bring down cash in US$ to get Pesos once you are in town... else you could pay a car service from Manuel Tienda Leon and use your credit card to pay for that, and deal with the forex trade once you are in town.