Calculates supplier allowances (Marketing, DDR, General Discount) and volume rebates. Generates credit requests and credit memos. Use when working with CalculationType (ItemCost, ItemCostWithCredit, ItemCostWithCreditAllowance), ForCreditRequest, Earned, Accrual metrics, rebate tiers/steps, PaidToTheFirst, Growth rebate types, PaymentOnReachingStep, or ConditionType (CreditMemo, DeductedFromPayment).