They do expect to be tipped. My family goes to Cuba every year so I've been there many times. You can pay in Canadian or US $$,but they do prefer to get paid in CUCs. Not sure where Salamander gets her info,but it is not true. They'll even take coins if you needed,but it is harder to exchange them in Cuba. Bills from US,Canada,UK and other popular currencies are gladly accepted and pretty easy to exchange for them