Actually, some of the above answers are correct, some are incorrect and some I don't know about.
I do know that in CA the requirements are a class C for under 10,000, endorsement for 10,001-15,000 and class A over 15,000. Now, that is for CA residents.
Generally speaking, you make sure you are legal in your home state. However, I am unsure how it works for other countries. I think it works the same, but I suggest you check with your local licensing agency to find out for sure.
Unless you are pulling a humongous 5er, I doubt you will have any trouble in any of the lower 48 states.
Come on down!