Different Cuban Currrencies
There are 2 currencies in Cuba: the Convertible Peso (CUC) and the Cuban Peso (CUP), also known as 'moneda nacional', 1 CUC = 24 CUP. You can get CUC by changing your currency at any of several official currency exchange office (CADECA), located at airports, hotels and banks.
It is advisable to bring EURO currency to Cuba, the USA Dollar has an additional tax of 10%, then 1 USA Dollar = 0.874 CUC. The CADECA for changing money at the airport has a higher tax than the CADECA on the street, so it is good to change only the necessary money for the first night in the CADECA at the airport and later changing the rest of the money in the CADECA on the street. The owners of rental houses don't ask to pay the rent the first night.
Most of Cuban shops have prices in CUC, for instance, if you want to buy cheese, ham, beer or rum, you will have to pay in CUC, but the fruit markets have prices in Peso Cubano, the same way some little cars with fruits which are on the street, in general fruits and vegetables have prices in Peso Cubano.