I have a thoughtful Thursday post queued for January 28th on using ID3 to select among other things a tax code. And I discuss applying genetic algorithms to determing tax codes and budgets.
I believe that voters should vote on a regular basis, not from time to time via referndum, on the rates for each tax bracket and for, at least the major classes of taxes (property, corporation, individual, sales and excise taxes.) The votes of rates should be combined by median. (median has a role in median income.)