User blog comment:12th Supernova/Chapter 793: Bad News and Bad Translations/@comment-4503935-20150709200130/@comment-2125188-20150709214151

This is my best guess for the bounty increases.

As for the others, I still need to see what they got up to all this time. I hope we see them again soon!
 * Luffy - 500,000,000: For defeating Donquixote Doflamingo and for his involvement in the Dressrosa incident (might be a little more).
 * Law - 450,000,000: Will be excommunicated from the Shichibukai for his involvement in the Dressrosa incident (minor increase due to the fact he didn't really do anything).
 * Zoro - 400,000,000: For defeating Pica and for his involvement in the Dressrosa incident (I know it's a very large increase and probably worth more then the action itself, but it's been a long time and he is worth at least this much).
 * Franky - 150,000,000: For defeating Senor Pink and for his involvement in the Dressrosa incident (hard to guess this one, but it would be somewhere around here more or less in my opinion).
 * Robin - 100,000,000: For her involvement in the Dressrosa incident (minor increase cause she didn't do much but still enough for a minor increase)
 * Usopp - 75,000,000: For defeating Sugar and for his involvement in the Dressrosa incident (I know he probably did as much as anyone, but I don't see the World Government looking at the positives. Probably in their eyes all he did was knock out a little girl)