What is the ruling on leaving the change for the seller or driver, and giving the cleaning worker extra pay as charity, and what is the meaning of the Hadith: "The one who gives more and the one who asks for more are in the Fire"?

If the giver is content to leave the remainder or the surplus to the worker or the employee, that is an act of leniency encouraged by Islamic law. As for "the one who adds and the one who seeks to add are in the Fire," its meaning is that whoever adds or asks for an addition in gold or silver when exchanging them has practiced forbidden usury. The forbidden increase is in selling these items for their like.