As GringoCarlos stated there are three exchange rates in the DR. The Central bank rate which is announced every Tuesday in Listin Diario. The commercial bank rate. Each bank sets it's own rate but this is dominated by some of the larger banks especially Banco Popular. There is then the out of bank rate which is usually the best rate. Included in this are remittance companies like Western Union and foreign exchange bureaus to the guy on the corner.