Just had a house built & talked to our builder about this very thing. He said sealing any tile is not necessary.Sealing any tile changes the color of the grout & the tile (darker) & it makes it hard to match should there be a need to replace a broken tile.In the showers he recommends scrubbing bubbles for cleaning.On the floors he says only water,we use a steamer.Make sure if you steam it the dirty water is either soaked up or vacuumed.