Yes, there are several banks and ATMs in the town of Jaco. Some of them allow you to withdraw dollars, but you can get colones, the local currency, in all of them. If you need to go into the bank for any reason, make sure you bring your passport. You’ll always need it to do any legal paperwork, and it will be your source of ID while in Costa Rica. (It must be the original; a copy will not be accepted.)