Bargains and bribes seem of questionable use when a power is willing and able to kill you and seize all your assets anyway. I suppose there's the odd Swiss bank account or successful smuggling case to deal with, or people willing to destroy their possessions rather than let them fall into the hands of a murderous authority, but I'd be surprised if any of these weren't fairly small minorities in the face of the total. We're certainly not talking millions.

Corruption at lower levels could have reduced the death toll of many famous genocides (in fact, I'd imagine it did), but at the level of Hitler or Pol Pot I can only see it helping if the bribes or bargains being offered are quite large and originate outside of the regions where the repression's taking place. Much like the present situation with North Korea, come to think of it.