When I began in retail the philosophies were: "The customer is always right" and "Give the customer what he wants." I have never been to a 'Jackie the Ripper' shop but I have had some salespersons cut some pretty strange angles. I usually get an 1/8 yard extra, just in case.
I think a 'Ripper' shop should accommodate you without charge if you prefer a cut edge. If tearing is a really hard core policy they could cut from the other end. The end of the bolt IS already cut, I think. It's not that hard to rewrap with plenty of counter space. Shops need courteous staff and satisfied customers to stay in business.