I have to agree, if you are looking to use this for a battle map with a 5ft grid, then either the tiles need to be 5ft square, or you should come up with something non-square that repeats every 5 feet. You could come up with a rectangular pattern that repeats every 5 feet. Might be a bit tedious or repetative though. But I think that would make play-ability (use as a battle map) much better.

I think if you search 12x24 tile patterns you will find some that repeat. Though you could also use a repeating pattern of triangles or other shapes too.