Hello.
As the owner of your AbanteCart installation, you have full rights to all the source code. This means you are free to modify any aspect of the code, including calculations, to suit your specific requirements.
We encourage you to share any improvements by submitting a pull request to our
official GitHub repository. This way, the entire AbanteCart community can benefit from your contributions, in the true spirit of open-source collaboration. Before submitting, please ensure that the solution is thoroughly tested with several popular payment providers and covers various scenarios, including cases with multiple items in the cart. This helps to avoid rounding issues, such as 1 cent discrepancies that can occur with quantities like 11 or 333.
Thank you for being a part of our community