Traditionally bookstores get 40% of the list price of a book. They have overhead to pay from that money in addition to earning a profit. Remember that they rent or own the storefront, they have employees to pay, and they have utility bills that arrive every month.
Don’t be surprised if a store asks for 45% so they can run special promotions.
Be flexible. Consider whether sales can help your brand by getting your name out there even if the store discount means you make very little profit yourself.