U' or U l' U' keeping one top slot open, this enables you to fill in all opposite side edges except one. If you have all the cubes on their correct inner slice and give it a little forethought you should only have to do it once to get then in their correct positions also. It will swap centers without mixing anything else up. If you know how to fix a 3x3x3 cube and learn this 4x4x4 method, you'll be able to fix anything including the 5x5x5 and whatever else they can make, All the moves are the same. The best part is you don't need to memorize hundreds of moves, you'll just know how to do it.
All corners are the same.
All outer slice edge moves can be used on any cube. All inner slice edge moves on the 4x4x4 can be used on the 5x5x5. It's the same Isolation move. Down Right Left Front Back Capital letters stand for the outer faces such as the front face, back face, down face, etc. Lower case letters stand for the slices just behind the outer faces, such as the inner front slice, inner back slice, inner down slice, etc.