Mining fees are out of control of the Cryptoprocessing. Mining fee is a fee that is paid to cryptocurrency miners for processing of transactions within a network and including them into a block, hence ensuring security of the respective network, that's why such fees are also called the network fees. In case of depositing the mining fee is paid on a side of a sender and we cannot influence it anyhow since the mining fee is set prior to sending a transaction to a network.
For withdrawals Cryptoprocessing uses an algorithm that calculates an optimal mining fee based on the current network load, basically we apply the medium mining fee that allows client to receive funds within a reasonable timeframe. However it shall be mentioned that mining fee cannot be calculated and provided prior to sending a transaction to a network, hence it can be checked only after receiving a callback.