As a rule I don't tip more when I'm faced with a "mandatory" tip, which is sad for the staff but it was their employer's choice to mandate it. This past week we had a going away party for a long term staff member, choice was a local Chinese restaurant many of us frequent and they opened up on their normal day off. When I went to pay I assumed they would slap on a mandatory tip, but alas they didn't! They were tipped much more for their service and trusting that we would tip well.