A taxpayer may not change to the LIFO method of taking inventories unless, at the time he files his application for the adoption of such method, he agrees to such adjustments incident to the change to or from such method, or incident to the use of such method, in the inventories of prior taxable years or otherwise, as the district director upon the examination of the taxpayer's returns may deem necessary in order that the true income of the taxpayer will be clearly reflected for the years involved.