A invoice system that I can use with vehicle registration

I am looking for a customizable invoice software that can be used with vehicle registration. The system should be standalone and not integrated with any existing software or platform. The most critical feature I need in this invoice system is automatic calculations.

Ideal skills and experience for this job include:

- Strong knowledge in developing customizable invoice software
- Proficiency in programming languages such as Java, Python, or C++
- Experience in working with invoice generation and automatic calculation features
- Familiarity with vehicle registration processes and requirements
- Attention to detail and ability to create user-friendly interfaces