To whom do I begin reporting the unprofessional behavior that occurs at my job?

If nepotism isn't against corporate policy I don't think there would be any reason to report that. If it is it should be reported. As far as unprofessionalism and morale issue my advice would be to be very careful who you report it to. Alot of times managment doesn't see things the way lower levels see it. I would just caution you to make sure you have some factual info that you can report and not just he said/she said type stuff. You don't want to put your job at jeopardy. Having said that, i'm not certain what type of store you work at and whether there is a corporate office but i would try to find out if there is a district manager or corporate contact. Alot of companies have an employee help line where misconduct and fraud type activiites can be reported, even anonymously. I've worked in corporate America for a long time, and I'm talking about highly educated people (who you would think would be very professional) but you will always run into that to some degree. It usually only takes a couple of bad apples to ruin the whole work envirnoment.