The whole point is that 'clearance' barcodes don't have a price stored in the database.
Every grocery store I've consulted for or worked at in my youth was operated the same way - there were "manager special" barcodes where the price was part of the barcode, and the price in the database was recorded as 0 with a flag of "barcode encodes price".
Every grocery store I've consulted for or worked at in my youth was operated the same way - there were "manager special" barcodes where the price was part of the barcode, and the price in the database was recorded as 0 with a flag of "barcode encodes price".