[Nettie Belle]

Is it an ok thing to accept tips at a paid thing or is that tacky?

Yesterday, I was doing face painting at a grocery store ... and they had already paid me, but some of the people whose children I had face painted insisted on tipping me and one lady was looking for my "tip jar"? Do you put a tip jar out for something like that, or is that tacky since the place had already paid me?????