We fill the tip envelopes while still at home, date each one, and rubber band them together. That way, each morning as we are getting ready to leave, I just drop the envelope on the bed.
I keep the rubber band stack in my make-up bag, so I don't forget to grab one when I'm doing make-up (never forget that), and we don't have to hunt for money!
BTW---I leave $5 a day (buck a person). I live in a tipping town, and work a tip job. We think it's important for our kids to understand about rewarding excellent service, and they enjoy decorating the envelopes.