Depends on what the fees are at the time. Gas fees aren't percentage based. I can sell for 10 eth and pay the same fee as for 15 eth. All depends on the market that day. In order for the transaction to go thru, it has to be validated by the people on the network. And if it's busy or eth had gone up in price, they gonna charge more on the gas fee to make their work worth it.
As far as taxed by the government goes, I'm just transferring the coins on metamask and sending to other wallets. Some of those transactions like to it ledger wallet, the government doesn't know about. It's like moving money from your cash app to your bank account. I'm just moving funds nothing else. You do get taxed when you sell back to dollars based on capital gains. Chapter if you hold for more than a year but the tax rate depends on your income. I think up to 40k is tax free but who knows if that might change with this administration, especially Biden and Yellen.