Site: nolo.com
... For example, a royalty rate of 2% of net sales with no deductions may earn you more than you would receive ... the size and resources of the company with which you are negotiating:
Greeting cards and gift wrap: 2% ... 5%
Household items such as cups, sheets, towels: 3% to 8%
Fabrics, apparel (T-shirts, caps, decals): 2% ...