I think the restaurant with the iPad menus in Japan isn't doing it yet, but if I had a very forward thinking restauranteur friend I would offer to A/B test to victory. Increase average ticket by 10% and you print cash.
But people don't want to know you're A/B testing on them with prices. Didn't Amazon get in trouble over that and have to back peddle? Seems like you have to A/B test over time and not offer different prices simultaneously or else you risk pissing people off.
you could just A/B test the difference between using $9.00, $9 and 9, for example.
You could also play around with sales tax where one menu has values of say $7.99 (tax not included) and another has $9 (tax included)