Part of being a grown up is the ability to graciously say "no, thank you" and move on without rancor.
Our local grocery cery store allows us to Round up for the Police fund. Unfortunately, the cashiers never ask any more, they just prmoted it when they first opened. But since I know it is an option and I wish to do it, I tell them I want to Round Up before they hit the buttom that makes it impossible. I know the store owner, he was on the Police Commision.
But I always say "No" to kids with cancer or muscular dysteophy, homeless families, pets without homes, (since I am still involved heavily in my own rescue groups) and I feel not one twinge about it.
While I think the ask by retail operations is off-putting to many of their customers, I also think it is a good teaching moment for the OP and his son.It is a great opportunity to talk anout planned giving and the importance of identifying YOUR causes to support, and not letting random dudes control which good causes get your resources. I say "no" e ause I have no guilt, I support the organizations I value.