Question: p1 posted his bank account info and was excited to announce that he has paid off his mortgage. He is asking others to post their bank accounts as well.

p2 "I have more than that but I have enough tact not to rub it in your face."

Answer: 
It means to inform someone or remind someone that you are superior to him or more fortunate than him in a way that is excessive to the point of rudeness. That is, you are not just pointing out your advantage, but emphasizing it in a way calculated to embarass the other person or build yourself up.
"Rub your face in it" does come from dog training but it has more do to with pointing out others mistakes and failures than it does flaunting one's own achievements.

I know this was a while back but I thought Jay really misled you on the meaning. No offense intended.