You are able to see how much Commission you are being charged when you open a trade on your MetaTrader.

Step-by-Step Guide

Desktop Computer: 

1. Click the Trade tab on the bottom of your MT4. 
2. You will see the Commission fee charged near your trade. 

Mobile Phone Device: 

1. On the Terminal, tap the Trade option on the bottom.
2. Tap the trade and you will be able to see the Commission charged.