Slots garner significantly higher tier credit than roulette on a table both in real terms and by ratio considering the house advantage. So if the tier is what you are after, you should concentrate on spending and playing slots. If you like playing roulette, there are some slot roulette machines in MGM and possibly elsewhere. If you are trying to get tier credit from playing roulette and must play at a table, I believe that at least at Bellagio, Aria, MGM and Mandalay Bay you need to bet at least $25 a spin to be rated (I assume you mean you are at a $10 min table but you do not state what your average bet is) and I think you have to be rated to be accruing tier credits.