CAT6 cable will be fine. It has better specs than CAT5 but typically costs 50% more.
If you haven't already purchased the cable, just use CAT5. It will be all that you need and you can even run Gigabit Ethernet over it.
If you're running cables for network inside walls/ceilings, especially in new construction, I'd go with the highest category you can afford, for future proofing.
But, to answer your question, CAT6 is fine for CAT5 applications.