Keep in mind that shelves must be restocked as well. Employees are putting their hands on most product's shelf space daily. Updating the prices while restocking

Keep in mind that shelves must be restocked as well. Employees are putting their hands on most product's shelf space daily. Updating the prices while restocking seems like an almost negligible cost. That said, I know some people that work in the grocery industry, and my impression is that the margins are tight enough that they do the math on EVERYTHING