We were discussing this question in the chat room, and came up with the possibility, gratias similiter, but we are not sure whether it's idiomatic. The context is this. Let's say a co-worker says to you, "Hey, you look sharp today!" You might respond, "Thanks, you too." How would you say this in Latin? What's the most idiomatic way of saying it?
This interaction to my ears is decidedly modern, and since most of Roman literature is not colloquial dialogue, it will be hard to find exact matches.
However, the request is very simple and overthought. The most common way to thank somebody is gratias agere. Though there are other ways, this is both common and commonplace.
If you want to say "you too!" to someone, there are two common ways: et tu (think Caesar to Brutus) and tu quoque. The thing is that "you too" is short for "you too are X" (in this case "you also look handsome!"). I don't know why you would any anything further to it, like similiter, and tibi quoque is certainly wrong, since that's dative. You're not thanking the person in addition to another, in which case gratias tibi quoque would work (i.e. "I thank you as well"). At any rate, similiter is used by Plautus once (and adsimiliter once).
To me, this is a case of just keeping it simple.