(a) A contractor's practices used in estimating costs in pricing a proposal shall be consistent with his cost accounting practices used in accumulating and reporting costs.

(b) A contractor's cost accounting practices used in accumulating and reporting actual costs for a contract shall be consistent with his practices used in estimating costs in pricing the related proposal.

(c) The grouping of homogeneous costs in estimates prepared for proposal purposes shall not per se be deemed an inconsistent application of cost accounting practices under paragraphs (a) and (b) of this section when such costs are accumulated and reported in greater detail on an actual cost basis during contract performance.