Hi,
I have analyzed your post and You need a plugin to calculate vat and tax and you want to use it multiple places or for sale.
I develop plugin from scratch according to requirements.
Ping me! Let's have a brief discussion over chat.
Thanks:)
Ravi
MY skills:
PHP, WordPress, Open-kart, Codeignitor, Woo-commerce, ASP.NET, MVC, C#, MSSQL, MYSQL, Database Programming, Bootstrap, Jquery, Front-end & Graphic designing, SEO.etc.