XRP Ledger fee
When setting trusts, creating orders (even unsuccessful ones) and transferring funds, changes are being made to the XRP Ledger, which consumes a small amount of XRP.
This is called a Transaction cost and is deducted from your XRP balance for any transaction.
"The transaction cost is not paid to any party: the XRP is irrevocably destroyed."
What counts as a transaction?
Actions on the XRP Ledger that count as a transaction are payments, opening a trade or exchange order, cancelling a trade order, enabling or disabling a trust line.
Please note that unsuccessful actions are also recorded as transactions on the XRP Ledger and are subject to transaction costs.
More information about the Transaction cost is available here.
Fees charged by GateHub
Gateways may charge fees for trading their IOUs on the XRP Ledger. This is a standard revenue model for gateways on the XRP Ledger.
See all fees charged by GateHub and GateHub featured gateways here.