Developed a scalable enhancement to the Shopify/ui-extensions repository by introducing an optional cash rounding adjustment field to POS transaction payloads. This addition, implemented using TypeScript and front end development skills, enables precise recording of cash rounding at the transaction level, supporting accurate cash handling and improved analytics. The approach maintained backwards compatibility within the payload schema, ensuring seamless integration with existing systems while preparing for future cash rounding features. By enhancing the data model for POS systems, the work supports compliance readiness and lays the foundation for smoother integrations with payment providers, ultimately improving the fidelity of downstream reporting and analytics.