The currency in the DR is the Dominican pesos. The current exchange rate is 42.80
Coins:
1,5,10, 25
Bills:
20,50,100,200,500,1000,2000
The best place is to exchange money is a private money exchange house, caribe tours or western union. They have the best rates.
Tips:
Always have pesos. I had girls who want to go out late at night, or take a taxi to come and see me and I had to pass, because all I had was dollars and no pesos
Always have small bills. Most places won't have change for big bills. I have taken many taxi for 150 pesos and they won't have change if I pay with 200 pesos.