To encode customers and give them preferential treatment with special prices you can do the following
Search the customer or create a new one from Database > Clients. Turn on the “Preferred Customer” option. From here you can scan a barcode if you have printed cards to give to customer.
Then select the price list that you want to assign
Scan customer when selling
Once the customer is set as preferred you can scan their card at the time of sell to speed up the process.