Ruling on giving a tip

Q: If I work in a pharmacy or any other place where I get my wage from the employer, but some buyers give me tips; what is the ruling on taking these tips without asking for them?

A: It is not permissible for you to take this money, for it is a kind of bribe, which is Haram (prohibited).May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.