I've played poker for a living the past 4 years now. I've maybe tipped somewhere around 12,000$ i would imagine in 4 years. Possibly more. Here's the simple facts: if your a low stakes cash player tipping is absolutely NEGATIVE EV. Plain and simple. If you play 7-8 hours of 1/2 or 1/3 remember your automatically paying 70-80$ in rake no ifs ands or buts about it. You add in another 20-25$ in tips more like 30-40$ from me (when i used to tip) that amounts to 100$+ every single day!!
The funny thing is, alot of you guys wonder why you can't beat low stakes poker. Hint, hint.. Here's some avg. Sessions. The reality of it is, I'm there to make money bottom line. If you can afford to tip or play the 2/5 game and up where rake isn't an issue then tip as you please. As for me, I'll be smart about it since i realize that every edge counts in low stakes hold em. Best of luck.