If you're being pressured to donate to your boss' Christmas gift, decline to do so with full confidence that you're adhering to well established workplace etiquette norms. The power dynamics/inequity inherent in the employee/boss relationship means that there’s too much chance that employees will feel pressured and resentful of having to buy a gift for the person who controls their paychecks. AND, it’s unseemly for a manager to benefit from his/her position in that way. (Summarized from AskAManager)
If YOU are the boss and have direct reports, put a stop to any gift giving from your employees to you.
That is all.