How do I level a wobbling floor cabinet?

I recently purchased this storage unit for my bathroom basement: http://www.walmart.com/ip/Tower-with-2-Cabinets-Shutter-Collection-Espresso/11079895. However, the basement floor is not level and the unit cannot sit level to the floor...other than pushing some towels underneath the storage unit to level it, what is a more aesthetic solution that will look neat and professional?