The commission for Fx is per 10,000 contracts. I am not sure what "basis point * trade value" means, but would interpret it as 0.0001 multiplicated with the contract volume. When commision is calculated with a complex formula, as with IB, you have the choice between either using a simplified average commission, here probably the 0.5, or calculate the real commission value by script. In that case set the Commission variable to the calculated roundtrip value per 10,000 contracts before entering the trade.