Accepting a bribe to give a customer a discount

Q: I work in a retail store. The owners intentionally mark up products by 50% because they expect customers to negotiate and ask for discounts. The actual intended markup is 20%. 

One day, a customer approached me about a product that had the 50% markup. I knew I had the authority to reduce the price down to the 20% markup. The customer said that if I gave him a discount, he would give me some money personally. I agreed, gave him the discount, and he gave me the money.