How could I create a grid system but without rounding up one number?

For example, I want to have a grid system where you can place buildings down. Each building has an x of 5 and a z of 5. So it should be place-able on a grid of 25x25, where each building can be placed on a slot of 5x5.

I know you could use:

math.floor() and math.ceil()

although I don't want to use these, as I need it be 5x5, not 1x1.

Thanks!