Can you Tip extra to a Real Estate Agent?

There is a house that just came up in Queens New York. The price is perfect and It got posted a few days ago online. Open House is Sunday and yeah.

I just saw the house today and tried to contact the agent, no reply, Until I sent him my Pre-Approval. He tells me there is Open House and The market is very Hot, The house have been bid above His asking price. Basically telling me, The house can go for about $200,000(Maybe..... The house is $899,000) more.

Is it Legal To tell him that you'll tip him for an extra $5,000, If he sells the highest bidding price to you.

Like if someone throws out $980,000 and is highest bidding. I want him to tell me and I'll buy it for a bit more and Tip him $5,000?

Is this even Legal? All of this is what my parents are telling me to do, I don't even know what or how to even say this in English >.>

Hallppp