1. A computer-implemented method for use in analyzing costs associated with relationships among entities, comprising: receiving on a processor, entity data corresponding to a plurality of entities, relationship data corresponding to direct and indirect reciprocal relationships between two or more entities, and activity-based cost data corresponding to direct and indirect costs distributable among the plurality of entities; using the entity data, relationship data, and cost data to construct, on the processor, a model of a costing system; using the model of the costing system to determine, on the processor, a cost allocation among the plurality of entities, wherein the cost allocation excludes double counting by avoiding reallocating costs to an entity that previously allocated or reallocated the costs; and wherein the allocation of costs is symmetrical among top level entities in the plurality of entities; allocating on the processor, a direct cost among a plurality of entities, wherein at least one of the plurality of entities has a reciprocal relationship with another of the plurality of entities; and repeatedly reallocating on the processor, indirect costs of the entities that have reciprocal relationships until all indirect costs are reallocated to entities that have no reciprocal relationships with other entities, and wherein indirect costs are not reallocated to any entity that previously allocated or reallocated the indirect costs.