Giving tip to shopkeeper

Few weeks ago I had an opportunity to eat at an outlet manned by a single person. I got into conversation with him, and learned that he was the sole owner of the shop. He will prepare the eatables in the morning and open his shop in the afternoon. His native place happened to be near my native place & that allowed me to ask him some other general questions regarding his family and life-style. At the end, I perceived him to be an honest person doing an honest job. When the time came to make the payment, I was overcome by a temptation. I wanted to see whether this man would accept extra money as a favour or not. I handed him 33% more money than I was supposed to pay. He promptly took it.

I was left waiting for the words such as,"I will only take what is due to me…" or something like that. I discussed this with my friend. He told that since the trend in every restaurant is to give tip to the waiter, the same criteria apply here. The extra money that I paid is like tip for him.

I had asked that person's daily income. He earns more than me….