It is a social custom in this country to give cash gifts, known as tips or gratuities, during the holiday season. How this custom came to be I have no idea. And while we see editorial suggestions in newspapers and magazines during the holidays, thankfully there are no rules, no tipping police. What makes one service worthy of gratuities from its patrons while others, such as grocery checkers, the nurse, and dental hygienists, are not included? I don’t have a definitive answer, but I do have some thoughts for your consideration that you may or may not find helpful. My goal is to get you thinking so you can develop your personal tipping guidelines. If you’re not sure who to tip, ask yourself: Can I afford to be without this person? By “afford to be without,” I mean, do you want to face the future without this person’s services? If …