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.

Going for holiday with family members who do not uphold the laws of deen

Q: We often go for long family tours in India and mostly we are in the bus. My family plays music in the bus so that the driver (not a family member) will not fall asleep and free mixing happens among cousins born in joint family. 

Am I allowed to join such family tours while observing hijab and closing my ears to not listen to music? If no, What should I do if my parents insist that I accompany them (it would cause them great sadness if I don't come)?