Tile isn't the only solution.....think outside of the box. With the corrugated metal walls, it sounds like you're going for a more industrial feel or a rustic feel. Have you thought of an industrial epoxy floor finish, something that would be used in a garage if you will. You can get them in solid colors or with added color flakes.....this might be a possibility.

Or you might consider stained/sealed concrete finish if you have a slab on grade. This could be enhanced with a cut tile pattern through out and different stain portions to simulate an inlay........

Actually your floor finish is wide open. It's apparent, with your choice of the corrugated metal wall finish that you're not going for standard.........why stop with the walls?

Secondly, you didn't mention it, but I'm wondering what sort of moisture control are you planning for behind your metal wall finish? I have used corrugated metal panels in showers before and the best performing system we found was using Gold Bond® BRAND e2XP® Tile Backer and for added performance we add a layer of Grace Ice & Water Shield. This provided a protective self-sealing of the metal panel attachments screws..........overkill, maybe, but the last thing a builder wants is a call from his client that the he has a problem.

I agree with Mr Kutch above that, if possible, a polished concrete floor would look unbelievable with the corrugated steel. If you do not have concrete under the floor etc, then you should look at perhaps some unconventional tiles. In addition to some other unusual textures and appearances, Hastings Tile & Bath makes tiles that are finished to appear metallic, and that could work really well. I uploaded a pic of one below.

http://www.hastingstilebath.com/tileproductsByCollection.php?catid=68