Owner is billing for procedures I didn't do

I've noticed the owner is billing insurance for procedures that either weren't done or were done differently than billed. Nothing major, but definitely not accurate. I'm an associate, not a partner. I don't want to be complicit in fraud, but I also don't want to lose my job or get blacklisted. What do I do? Do I confront him? Report it? Just keep my head down and look for another job?