50% 10x would be 3.33%, which is solid for a bonus.
Bookmaker even at their 15% for Platinum (that is the last bonus I saw before they pulled that and betpoints) was a nice rebate combined with their betpoints. I think it was 5x on that tier (want to say it was 4/5/6 for roll on their tiers?) so that is roughly 2.6% and their betpoints on Platinum was another .6%ish so you were getting over 3.2%. If you are finding +EV bets, great add on. If you are not, cut what you had to hit to be profitable.
Bonus (cash)/total roll gives you the "rebate" (bonus). If it is FP, assume you get a bit better than 50% of the FP in cash and use that (depends on their rules for what you can play).