For fans (and venues)
What that cover charge actually pays for
A $15 door isn't all profit for the venue, or the band. A few things come out before anyone gets paid.
1. Songwriter licensing
Any venue that hosts live music needs public-performance licenses for the songs played, including covers. In the US those come from four organizations, each representing a different catalog of songwriters: ASCAP, BMI, SESAC and GMR. Full coverage means four separate annual fees, scaled to capacity and how often there's music. Venues that skip it risk statutory damages of $750 to $150,000 per song, and the licensing groups do sue small venues.
2. Minnesota sales tax on admissions
Tickets and cover charges to entertainment events are taxable in Minnesota at the general sales tax rate (6.875% statewide, plus any local taxes). See the Department of Revenue's Ticket Sales guide.
3. Minneapolis's extra 3%
Minneapolis adds a 3% entertainment tax on admissions to concerts and similar events anywhere in the city. It's separate from the city's downtown-only liquor and restaurant taxes. See the state's fact sheet, Minneapolis Special Local Taxes (PDF).
What's left
After licensing and taxes, the rest of the door is split between the venue (staff, sound, rent) and the artists, usually under a deal agreed in advance. That's why buying a ticket, rather than just showing up, is one of the most direct ways to keep a room open.
Informational only, not tax or legal advice. Rules and rates change; the official sources linked above are the authority.