Before I begin, let me say this: the rollover program is only valid for people who have submitted any number of coins into at least five caragories. And, I must also say that you can do this only once.
So here is how it works:
Instead of submitting two coins in a catagory, you have the option of submitting one (or none). One of those spaces that you are not using can go towards another catagory. Remember, this is valid only once.