A restaurant cashier is responsible for greeting customers, managing the billing process through the POS system, handling payments via cash, cards, or UPI, and issuing accurate receipts. They must maintain a balanced cash drawer, keep daily sales records, and report discrepancies. The cashier coordinates with kitchen and delivery staff for order processing, ensures cleanliness and organization of the counter, stocks billing supplies, and follows company policies on transactions, refunds, and discounts while maintaining customer satisfaction and data confidentiality.