California Wal-Mart customers who spot any price-scanning errors will get $3 back at the cash register. The deal, which is part of a settlement with California’s attorney general and San Diego’s district attorney, is a response to customers being overcharged across the state. County Departments of Weights and Measures found that 164 Wal-Mart stores in 30 counties had made scanning errors, overcharging customers an extra $8.40 at checkout, on average.