To control the coverage computation, you can use the considerLeavesOnly Tag.
When creating a Requirement Hierarchy Table from the ReqXChanger menu, the considerLeavesOnly Tag is created and set to true.
Set to true, it does only consider leave requirements for coverage and skips requirements which contain other requirements (usually headings).
If the Requirement Hierarchy Table is not created from the ReqXChanger menu, the considerLeavesOnly Tag can be added and set to true to consider leave Requirements for coverage.