Bittrex has (for Bitcoin WITHDRAWALS): 0,00100000.
It means that i have to pay fees to transfer from Bittrex to my ledger, for have the safe!
If i have 0,05 bitcoins to transfer, that means i must pay $13 of fees to Bittrex??

That's right??
Unfortunately that's right. It's a fixed fee set by Bittrex for every Bitcoin withdraw and there is nothing you can do about it.