This is one of those things that's up to you. The camp counselors are salaried, as opposed to the cabin stewards/staff and wait staff, who depend on tips for most of their income. I've read posts where people have tippped the counselors $10 per day and others who have not tipped at all. There's no right or wrong here. If you want to tip, go for it. If you don't, don't worry about it.