in episode 531 when you see the strawhats' wanted posters, Robin's bounty looks like it's B. 100,000,000.
I know I could be wrong and those could be the last 6 digits in her bounty, but we haven't seen Robin's FULL bounty after the timeskip. We see her poster, but not her bounty. I'm just saying that being with the revolutionaries for 2 years might have increased her bounty.