In the context of a Public Sector agency leveraging the Business Rules Engine for Licensing & Permitting, where multiple permits are allowed for a single application with permit fees calculated based on the selected types, the appropriate steps involve data aggregation. An Aggregate step with a SUM function is used to sum up the total value of all selected permits, addressing the need for dynamic fee calculation. Adding an Aggregate Group to the end of the Expression Set organizes these calculations effectively, ensuring that the total permit fee is accurately computed based on the application's permit selections. This approach aligns with Salesforce's Business Rules Engine capabilities, which allow for complex data manipulation and aggregation to support varied business scenarios, such as permit fee calculations in a Licensing & Permitting implementation.