There are some online casinos that will charge a small percentage of each deposit as commission. This charge is meant to cover the cost of the transaction. Of course, many casinos pay for it themselves, but some go a different route. Whether you wish to pay extra is up to you and you could always switch casinos. There are also such online casinos that forgo this commission for players part of their VIP clubs. This could also be an option that you could explore as it comes with many other benefits.