It will help a little but won't cover the lines completely. If the grout is the same color as the tile it will show less than if you're using a colored tile and white grout for example. How many tiles are you talking about. If its just a few, try putting some grout on and see what you think. Not that much harder to remove the tile with the grout on. If you've done a whole wall, it would be a major PITA to take them all down.
