<human>: Since the beginning of the year I have been doing some part-time sales for a friend's screen printing company. We mostly produce things like t-shirts, signs, and uniforms for teams/businesses; but we can and will print just about anything you could possibly think of.

I have been receiving 10% commission, which seemed a bit low to me(I would've thought 15%). I was doing this almost as a favor, though, and mostly working at my convenience so I didn't think much of it. I was generally only making a couple sales a month and the extra money was just a nice bonus.

Recently, I had a customer place their second order of the year with me, to the tune of almost $6,000. When it was time to get paid, my boss/friend informed me that for repeat customers, commission is 5%. 

I thought that seemed ludicrous, but I took a grin and bear it attitude, wanting to find out all I could about typical commission rates before I confronted him about it. I've known this guy for years and wouldn't think he'd be the type of person to take advantage of me, but it sure seems like that's what he's doing.

What are typical commission rates for a new salesperson? I'll take answers from people in any sales field, but would love to hear from someone with experience in the same industry.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Doing part-time sales for a friend's screen printing business. I'm getting 10% commission and he recently told me I get 5% on sales from repeat customers. Am I getting ripped off? What should I be making?