I hate Tip Jars.

That having been said, if my change comes to less that 50 cents I'll likely just toss it in the jar since I don't want in my pocket all day. More than 50 cents? I'll likely keep the quarters and toss the rest in.

Would I ever take money out of my pocket to put in? No.

I also consider myself generally a good tipper in sit-down restaurants, and usually leave close to 20% for good service. Bad service? 2 pennies and I figure they'll get the message.