You're paying commission twice; to get in and get out.
$ 2.00 is your minimum per TRADE.
This might help:
https://www.interactivebrokers.com/en/index.php?f=commission&p=fx
So, conclusion is that when I take profit of half my position, unlike Forex brokers, I have to oay more commission than when I take the whole profit. Am I correct? If this is true, it doesn't make sense to me...IB isn't an MT4 forex broker ... what matters is the spread + commission ... hope you finally are getting it now ...