Design a variable cost allocation model for an international joint venture between [Company A] (based in [Region A]) and [Company B] (based in [Region B]). The model should detail how costs such as logistics, distribution, and local marketing will be allocated based on each company's operations in different regions. Define the parameters for allocating costs according to market size, sales volume, and region-specific pricing strategies. Ensure that the allocation model allows for adjustments based on changes in exchange rates, local tax rates, or regulatory conditions.