If you have tile flooring with a textured surface, and you want a smooth surface instead, consider adding polyurethane to the surface of the tile. This is the same material that's used to provide the gloss surface to wood floors. It will add shine to the tile and fill in the texture of the surface.
Things You'll Need
Belt sander with medium sandpaper
Extra fine sandpaper
Use your belt sander, with medium sandpaper, to rough up the surface of the textured tile. Don't attempt to sand the finish off, but just de-gloss, so the polyurethane will adhere.
Apply polyurethane to the tiles with a paintbrush, in a smooth, thin layer. Do not apply polyurethane to the grout lines.
Allow the polyurethane to dry for eight hours. Use extra-fine sandpaper to buff the surface, turning it slightly milky.
Apply a second layer of polyurethane in the same way you did the first. Continue adding layers of gloss, buffing each before adding the next, until you are happy with the finish of the tile.