You will be able to find how much commission is being charged on each trade by:

 Desktop:

After you Buy/Sell a pair/instrument, you will need to go to the Trade section as shown below, you will then be able to see the amount of commission on the right-hand side.

 Mobile:

You will need to tap/click on the terminal button.

Then you will need to tap/click on the pair/instrument so you can see how much commission has been taken. 

You will see the commission taken on the bottom right-hand side of the pair/instrument you are trading.