Fees aren't fixed per block, and they're also not a percentage. Exchanges and Bitcoin software suggest a fee that ensures a quick confirmation, but you can choose whatever fee you want. Transactions with a higher fee are prioritized by miners, because then they make more money. Coinbase always uses a really high fee (around $3.50), so your transactions are always confirmed as fast as possible. I made a few transactions recently where I set the fee to $0.20, and it just took a few hours before it was confirmed.

So if it's not urgent, you can send $2 million USD with a fee of $0.20.