I don't use Coinbase much.
Is there a way to include a transaction fee when sending bitcoin from Coinbase?
Does Coinbase warn you if the transaction you are sending is low priority and should have a fee?
accidentally left an amount just under .01 on my account so i tried this for you
" This transaction requires a 0.0005 fee to be accepted by the bitcoin network. Do you want to add it? (This fee does not go to Coinbase.)"
seems they are forcing at least default fees
not sure if they include it themselves (or give you the option to include yourself) on larger transactions. i know they did not in the past but it's been a bit over a week since i withdrew anything