Do you mean Bitcoin/Altcoins exchanges trade fee (they have like 0.00001BTC on any trade exceeding 0.001BTC, which isn't much),
i think a bit of clarification is needed:
the trading fee (Bitcoin/Altcoins exchange fee) is a percentage of your order size not a fixed amount so if you for example buy 10
BTC worth of an altcoin you have to pay 0.02
BTC as fee if the fee is 0.2%
and if you buy 0.01
BTC then you have to pay 0.00002
BTC fee