Windows Billing & Inventory Software

I need a Windows-based billing and inventory management software.

Key Features:
Billing Module:
- Invoicing
- Tax Calculation

Inventory Management Module:
- Stock Tracking
- Product Categorization

Ideal Skills & Experience:
- Experience in developing Windows applications
- Proficiency in billing and inventory management software
- Strong background in UI/UX design for desktop applications
- Knowledge of tax regulations and invoicing processes

Please provide a portfolio showcasing similar projects.