I've noticed on the last couple of bills that the surcharges and taxes are not the same for 3 users on the account. We all have the same access and only one has the "Family Base" charged to their portion of the account, not me, yet my Surcharges and Tax was the highest of the three. How are all the Surcharges ans Taxes accounted for and billed? Why are they not the same? How are they computed?