I'm only aware of 5 cents off when u bring your own bag + 50 pc points that tag with the $0.05 after 2-3 days, then +50 pc points when they give u that +$0.01/-$0.01 on your bill. Total $0.15 per reusable bag that u bring. (50 points = $0.05)
I'm not aware of any limits on # of bags u can use. Have fun!