"The Defendants, USDA and the Cigar Association of America, on the other hand, point out that FETRA requires the USDA to adjust assessments periodically based on changes in gross domestic volume, not fluctuations in federal excise tax. They correctly note that the Step A methodology or mechanics of calculation were developed by USDA based on clearly discernible guidance from the statute. See 70 Fed. Reg. 7007 (2005). Defendants further stress that the periodic adjustment requirement was clearly intended to reflect changes in domestic volume. As to the use of the 2005 FET as a constant in the Step A FETRA equation, and gross domestic volume as the variable factor, the extent of congressional direction becomes a bit less clear. The Defendants observe that FETRA contains no clear congressional directive prohibiting the Secretary of Agriculture from using 2005 FET as a constant conversion factor in the algorithm. Furthermore, the Defendants hasten to add that despite Plaintiff's contentions, no subsequent congressional enactments, or failure to act, provides direction to the contrary. At core, it is Defendants' position that while FETRA provides specific guidance as to the computational framework for assessments, the mechanics of calculation reside within the purview of the Secretary of Agriculture under § 519a(a). With respect to this facet of the Chevron analysis, the Defendants seem to hold the stronger hand."