How can I get a finished look on the edging of a tiled shower?

Oh, drat. A common lament from the big box shopper.  Don’t get me wrong, they have their place and I love and patronize them, but this is exactly the kind of thing folks run into and there is no one equipped to help. Check on the boxes you have or that they have in the store.  Hopefully you can get info on the manufacturer and then contact their website to direct you to a tile supplier who will have access to the full line.  Hopefully that will do it.  If not, bring them a few tiles and I ‘m sure they will be able to hook you up with a good solution for your dilemma.