(c) Taxes on property (see paragraph (b)(5) of this section) used solely in connection with either non-Government or Government work should be considered directly applicable to the respective category of work unless the amounts involved are insignificant or comparable results would otherwise be obtained; e.g., taxes on contractor-owned work-in-process which is used solely in connection with non-Government work should be allocated to such work; taxes on contractor-owned work-in-process inventory (and Government-owned work-in-process inventory when taxed) used solely in connection with Government work should be charged to such work. The cost of taxes incurred on property used in both Government and non-Government work shall be apportioned to all such work based upon the use of such property on the respective final cost objectives.