Problem with weighted average calculation

Our weighted average at the item branch level has been being miscalculated for selected stockroom items beginning Feb 24 of this year. Due to an employee using a wrong data entry practice, receipt transactions were doubling tax.

Our standard practice has been to assign a land cost rule for tax and assign the rule to an item at the item branch level to roll up tax into the product’s cost at time of receipt. Unfortunately, one of our users additionally coded these lines with a tax code = “U” and a tax rate area = “KYSTATE” causing the item ledger to book tax twice. About 2000 records have been affected.