Sticky tiles are never cut quite even. Latex caulk. Force between tiles with putty knife or old card. Wipe with damp sponge. Looks like a pro job & seals out dirt and water so the tiles are less likely to peel up.
Found this idea on Pinterest. Sticky tiles from Home Depot under the kitchen sink! So much easier to keep clean! Love it! http://www.familyhandyman.com/DIY-Projects/Home-Organization/Bathroom-Storage/diy-bathroom-storage