Comprehensive POS System Development

I need a macOS desktop application for a POS system. This system should efficiently track:

- Laybys
- Trade-ins
- Stock
- Repairs
- Accounting reports
- Inventory management

Additionally, it must integrate seamlessly with my existing:
- Accounting software
- CRM
- Inventory management system
- Layby, trade-in, repair, and finance modules

Ideal skills and experience:
- Proven development experience in desktop applications, particularly for macOS
- Strong background in POS systems
- Familiarity with integration of multiple software tools
- Knowledge of accounting and inventory management principles

Please provide examples of similar projects you've completed.