It seems the only place to get the execution commission for an API order is in the 'order state' structure, the problem is, how do you know when the last 'order state' (which actually arrives as part of an 'open order' message) arrives? In my testing, I see a multiple 'filled' statuses with zero shares remaining with accumulating commission fields, there seems to be no way of telling which is the last one...has anybody else solved this problem?
Aren't you able to retrieve commission details for a potential order by enabling the "what if" parameter?