I accidentally took a money tip...(haha i know how do you do that?)?

I know,Im a courtesy clerk at a store and the old lady's keep trying to give you a tip even though you can except it! My advice: Except the tip only if it is below $5 and they keep bugging you about accepting the tip,and make sure none of your coworkers are looking or standing by you.Also,if possible.Drop the tip out of her hand.Pretty much grab the dollar and once the person lets go you also let go and let it drop and then pretend like you found that money on the ground, that's what my supervisor told me to do if I didn't want to get caught,lol. But good luck!