1. A method for chargeback cost allocation in an information technology (IT) system including multiple resources, the method comprising: using a hardware processor for: monitoring system resource usage and categorizing cost attributes of different resources into multiple levels defining a cost attribute hierarchy; defining different chargeback groups for the resources with similar cost attributes and associated chargeback policies at different levels of the cost attribute hierarchy; and performing chargeback cost allocation based on user-defined cost-allocation policies by allocating a cost for the resources at each hierarchy level of the cost attribute hierarchy independently using chargeback policies defined for the resources at a particular hierarchy level of the cost attribute hierarchy, wherein chargeback rate r is at time t is represented as r t ∝v t /V, where v represents volume of usage for a particular resource and V represents total volume of the particular resource, wherein performing chargeback cost allocation comprises: using the hardware processor for computing cost allocation based on monitoring usage data from individual resources monitored, wherein a final cost allocation is determined using a hierarchy of different chargeback policies, and total chargeback cost C is represented as C = ∫ 0 V ⁢ r t ⁢ ⅆ v = k · ∫ 0 V ⁢ v t V ⁢ ⅆ v = k 2 · V , where k is an integral constant.