Withholding Tax Suite app

I am working with the Withholding Tax Suiteapp. I am having an issue with a specific Taxcode/group which is Algeria 30% (article 76). The way that is set up is 30% 2%. There are 2 tax codes 30% of the full Amount and then 2% of the remaining (I believe?) The end result for the total tax rate should be 31.40% however NetSuite is calculating 31.52%. I am looking for someone who is familiar with this tax code and why I would be getting the error.

Thank you in Advance