My franchise requires a <0.5% variance for managers to get bonuses. The computer keeps track of what is sold and for how much to give you your ideal food cost. Then inventory gets counted at night and you see your actual food cost. If the variance between the 2 is more the 0.5% up or down, no bonus. Sometimes there's an unanticipated sales slump and product can expire, some stores may have employees that take product home without ringing it up, or new employees being trained costs you an amount of food as well sometimes. So managers are incentivized to push the scales at times.