Makwa's right... while some sites are OK on reward points and bonus clearing even at fairly low stakes (though some aren't), rakeback only gets you an amount based on the rake that's actually taken. At micro stakes, even if a rake is taken your share of the rake is then going to be insignificant.
However, once you're playing at stakes where rakeback will actually accrue, then it's possibly worth noting that it does change the applicable strategy slightly. Although one problem with playing a very tight game is not getting action when you do make a hand, the other part of the problem is that you pay out too much in blinds for the amount you get back because of that limited action. While there are some rakeback deals that only count 'contributed' rake (only counting hands where you contribute money to the pot), most work on the basis of whether you were dealt into the hand, and that supports tighter play, because it offsets the cost of the blinds.
In No Limit or Pot Limit games, it's more significant, because at an aggressive take you could see the rake being relatively large compared to the blinds, so the rakeback covers more of the blinds. Theoretically at the right table you could turn a profit without playing a hand from the rakeback paying out more than the blinds are costing you, though I doubt anyone here has found a situation like that in reality. Also consider the player points that you accrue to further offset the blinds, and the ability to multi-table more easily when playing very tight poker (because you're seeing less hands at each table), and this may further justify trying a very tight game with a rakeback deal.