1. A method of using rules to execute periodic allocations of funds in a hierarchal accounting structure, the method comprising: receiving, by a computer system, an allocation rule, comprising: a source account; a rule for determining a first amount from the source account; a parent account; and an allocation basis that uses characteristics of one or more child accounts of the parent account to determine a proportion of the first amount to be allocated to the one or more child accounts; populating, by the computer system, from one or more financial ledgers in a relational database system, at least a portion of a multidimensional data cube with data associated with the allocation rule, the multidimensional data cube comprising: a hierarchal arrangement comprising at least the source account and the target account; and aggregated balances for each level of the hierarchal arrangement; generating, by the computer system, using data in the multidimensional data cube, an allocation scenario, wherein: the allocation scenario queries the multidimensional data cube for the aggregated balances; the allocation scenario executes the allocation rule by calculating the first amount and allocating the first amount to the aggregated balances for the one or more child accounts according to the allocation rule; and the allocation scenario generates result values for each account affected by the allocation scenario; generating, by the computer system, one or more accounting journal entries that update each account affected by the allocation scenario with the result values; posting, by the computer system, the one or more accounting journal entries to the one or more financial ledgers in the relational database system; and updating, by the computer system, the multidimensional data cube to reflect changes affecting the aggregated balances resulting from the one or more accounting journal entries posted to the one or more financial ledgers in the relational database system.