The Total Cost for this Task. It will be null if we have null for each cost: MaterialCost, LaborCost, EquipmentCost, SubcontractorCost.

Public ReadOnly Property TotalCost As Nullable(Of Double)
	Get

public Nullable<double> TotalCost { get; }

public:
property Nullable<double> TotalCost {
	Nullable<double> get ();
}