Edit2: Lots of people are saying it's not possible to find a +EV strategy. I wouldn't be so sure. There can be all kinds of problems with the implementation of a dice game. PRC dice used to roll high numbers more often than low numbers due to a bug, and so it was possible to have a +EV game just by rolling 'hi' every time. I can imagine a game where your payout is rounded up to the nearest satoshi rather than down, such that a 60% bet ends up paying 2x for small bets. That would be +EV. And so on.
But that will only be the case with sites which have a fault in them and the person is exploiting that flaw. The method on its own wouldn't be +EV , and since substrata already mentioned that it doesn't involve taking advantage of a flaw, we can rule that out.