Different method (tested, works), code is in lite-C:
Code:
void vec_rasterize(VECTOR* _vec, var _number)
{
	_vec.x = _vec.x - (_vec.x % _number);
	_vec.y = _vec.y - (_vec.y % _number);
	_vec.z = _vec.z - (_vec.z % _number);
}