When paying with card in the US the server/bar-tender will swipe the card then bring it to you to sign and add your tip amount and new total. This new total is taken some time later (when?)
When I was there a few weeks ago I took a screenshot of a few transactions to check if they have been updated. I checked these yesterday. All but one have been updated with a new (expected) total. I think it would be useful to get a notification and a message within the transaction pay that the payment has been updated by the merchant.
This will help track spending as well as and confirm that the expected new amount was taken.