The Cuban Convertible Peso (CUC) is pegged to the US dollar, 1:1 but when you exchange your dollars for CUC, you will be charged a 10% commission since the bank likes to make money too.
Despite what you have read on Google, It is not necessary to convert US dollars for another currency before departing for Cuba.
Cuba has a dual currency system, Peso Cubano (referred to as moneda nacional, abbreviated MN) and Peso Convertible (referred to as CUC$). In general, travelers will pay almost exclusively in CUC, so it is not necessary to get Peso Cubano (CUP). For CUCS, try to ask for some smaller bills like 5s and 10s as sometimes local vendors or souvenir stands are unable to break 20 notes. You cannot get Cuban Pesos outside of Cuba.
U.S. credit cards are generally not accepted in Cuba, and even so you would not be able to use them in many places (it is an evolving situation). Cuba is still a cash economy so we recommend that you bring all the money you will need for your trip in cash. Bring a credit card for emergencies only. In some government shops, in major hotel chains and in some of the more upscale paladares you should be able to use a credit card, if the Internet is working.
Cuban bureaus de changes are called Cadecas. Only exchange at Cadecas or a major hotel chain. Make sure that you receive a receipt for the transaction and count your change. Do not ever change money on the street; these hustlers are trying to fleece you with money-changing scams. After you have exited to the arrival hall at the airport, you will be taken directly to a Cadeca to exchange money.
You may bring an unlimited amount of money to Cuba but you must declare amounts that exceed US $5,000.
A few scams to look for while in Cuba.
Make sure to check your restaurant bill to make sure that only the items which you ordered are on the bill. When paying in CUC, make sure that the change you get back is also CUC and not CUP (the national currency). It is common to give change back in Peso Cubano which is virtually worthless.
SOUL OF CUBA
9 Days / 8 Nights
Havana / Santa Clara / Sanctí Spíritus / Trinidad / Bay of Pigs / Havana /
SANTIAGO AND EASTERN CUBA
9 Days / 8 Nights
Bayamo / Guantanamo / Santiago de Cuba / Baracoa / Playa Pesquero /