With any transactions on the Cardano blockchain, there are a few fees that occur. These are known as gas fees. This guide will tell you where that little bit extra goes when making a sale or linking your wallet.
Sale of an asset - Once you have made your first sale of an asset you will notice you will receive a little less than the original price you listed the asset for. This is because we take 2.5% commission (min 1 ADA) of each successful NFT sale. There is also on some projects a royalty fee paid to the creator of the project. You can find more information about this here.
There are separate fees for Smart Contract listings which can be found here.