POSitive can support two monitors; one that faces your cashier for ringing up the sale, and one that faces your customer.
OVERVIEW
The customer's flat-screen monitor acts like a pole display, yet it displays much more information. Each individual item is displayed as the sale is being rung up, plus the tax, total, and tender are displayed at the end of the sale. When the register is idle, (the cashier is not creating an invoice) special full-screen pictures will be displayed in a slide show which you can control. You choose what pictures you want to "advertise" with and when they will be displayed. They could be of specific products, photos of your staff, special messages, etc.
See: Multi-monitor Station Setup, Multi-monitor Advance Setup, or Multi-monitor Layouts.