We have a legal binding from taxation department that the sales tax must be calculated on the Maximum Retail Price.
Currently Dynamics 365 calculates sales tax on the net amount of product after discount which is not as per the legal binding and tax authorities have sent a notice to the business that if this requirement is not met then your business will be penalized or even may suffer closure.
This issue has become business critical for us as our business has to bear penalty or closure due to this.
i would request Microsoft to provide a solution to this problem as more and more businesses are facing the same issue.