Will I be charged for canceled or rejected trades?
Canceled or rejected orders do not count towards free trades, and are credited back.
However, please note the following scenario: Let's say you have used 2 free trades, and then you place a limit order on say TSLA stock. The order will go as the third free trade for the month. Now while the limit order is waiting to be filled, let's say you go ahead and trade AMZN stock. You will be paying a commission on that AMZN trade since your free trades have been used. Later if you cancel the TSLA trade, you will get a free trade credited back in your account and you can place another trade commission-free in that billing cycle.