Whenever I buy fabric at JoAnn's, I ALWAYS buy extra because it is always crooked. 30 yrs ago when I worked a Joann's they had mechanical fabric measurers that you ran the fabric thru that measured it for you. If they're so concerned about accurate measuring - they should go back to those. The LQS that i go to is always more accurate than JoAnn's.
JoAnn's tried to charge me for 8 extra inches on some decorator fabric that had a 24 inch repeat on my latest valance project. I paid for a certain amount, the transfer paper said the amount sent was what i had ordered and I wasn't going to pay for it. I had used my teacher discount, but didn't have the paperwork w/ me and she wasn't going to give me that either. There was a place where the repeat was going to be wasted and when I said I didn't need it and i I wasn't going to pay extra for it - cut it off. The clerk looked annoyed. DUH!! Not sure how JoAnn's is going to "make money" on an 8 inch piece of decorator fabric that has a 24inch repeat, but they once again pushed me out the door.
I would rather have the fabric store increase the price by $1/yd and "give" me the extra inch or two than make a big deal about making me pay for it.