point of sale 
(abbreviation POS)
noun
The place at which a retail transaction is carried out: refunds will be provided at the point of sale...
- The 15 cent levy will apply at the point of sale in supermarkets, shops, service stations and all sales outlets.
- Currently we are not aware of any process outside of retail that provides reliable age verification at the point of sale.
- The original point-of-sale programs supported multiple stores by updating a set of master files through a complicated operation involving transaction files created at each store and a batch update process.