This is really up to you. Some people install laminate and some don't.
I would install laminate on the sides, the front, and (possibly) on the inside edges, if I had enough left over. But I wouldn't mind just painting the inside edges, since it's such a small area and easy enough to paint.
I would never bother installing it on the top and back unless I had an unlimited supply of really cheap laminate. IMO, quality laminate like Formica is the best finish for a cabinet, but its cost is a consideration.
Wade