If you are going to install ceramic tile on a counter or shower surround, it makes for a nice finished look to get finished round over or bullnose tiles (for kitchens they are referred to as V-cap tiles). Some styles of tile do not have these and so you may be faced with the chore of making them look good at an end point.
For a shower surround you can use a border tile. This would be a tile that would complement the field tiles, but does have a round over finish.
The other option is to apply grout at a 45-degree angle between the wall and the top edge of the tile. This essentially covers up the unfinished edge.
For a corner on a counter-top or shower pan where you have a flat surface going over to a vertical surface you are faced with a different problem. Without a rounded finished edge, you will need to get creative. Imagine the unfinished edge staring back at you. That would be pretty ugly and certainly the sign of a novice. What you can do is grind off the unfinished edge at a slight angle so that when it comes time to grout the area, you can simply fill the void with grout. Grind the area from the top finished edge of the tile (don’t touch the finished edge) and remove a small amount of the tile under it. The grout will match all the other grouted areas and will look nice.