I don't remember where I just read a post about a tip jar sitting out on the bar or who posted it, but thank you!! I just got my contract from our bar vendor and in small print it says they will have a tip jar set out. I emailed them back and told them I didn't want it sitting out or behind the bar. I told them I would pay the tips myself!! So make sure you read the fine print.
Re: Open bar/tip jar ***UPDATE*** in comments
Also, good for you for making sure it is in writing. If you are having a DOC or venue coordinator it might be worth mentioning to them as well so they know it is in writing.