Imonggo - The most cost effective point-of-sale solution for small and medium businesses.
Floreant POS - Floreant POS :: Open Source Point of Sale – Think POS Think Floreant
eHopper POS - The eHopper POS system is developed with small businesses in mind.
Lightspeed - retail and restaurant point-of-sale, ecommerce, and omnichannel solution
PHP Point Of Sale - Point of Sale software
Pipedrive - Sales pipeline software that gets you organized. Helps you focus on the right deals, so easy to use that salespeople just love it. Great for small teams.