The local currency is the Costa Rican Colon (CRC), which averages between 500-600 for 1 USD. But luckily, most of Costa Rica will always accept USD, but you must be aware of the exchange rate to make sure you are getting the proper change. If possible, when paying in cash and the price is in Colones, try to pay in colones; that way, your change will be exact. There are establishments whose prices are in USD, but most will give you a change in CRC even with that.