Currency conversion in Cuba

Here's the brief from Ciara's original post:

• Cuba has 2 currencies, CUP(for Cubans) and CUC(for non-Cubans)
• 1 USD = 1 CUC = 24 CUP
• You probably won't have to deal with CUPs, unless a Cuban gives you change back - be sure to check your change. CUC and CUP look VERY similar, so it's easy for Cubans to short-change you if they desire
• It is not possible to get CUCs before arriving in Cuba, so you will need to exchange your money upon arrival. You can exchange your money at the airport
• ATM machines are available for use for non-US visitors, but the lines are typically very long
• Note that US debit cards do not work at Cuban ATM machines so US Citizens will need to exchange all of their money at once
• TIP: There is an automatic 10% penalty when you exchange USD to CUC conversions, so it's recommended to exchange your US dollars to Euros before arriving and THEN exchange your Euros to CUC