I've always tipped, $2 to $5 and $20 if I happen to be flying on Christmas. However, I truly think tipping should go away. TIPing started as a way to avoid paying people a proper wage. If you want to go way back, it started as a way to avoid paying newly freed slaves.

Not sure why it became something considered a must do, but business owners are laughing all the way to the bank as the push costs off to the customer. Potentially as late as your [great?] grandparents generation, Tipping was considered deeply un-American