I’m afraid that’s not possible natively in Asana, though you could do it with the API and custom code.
Asana offers sums of tasks’ numeric fields in a section in a project’s list view, the various dashboards offer number charts that are sums, and portfolios offer roll-ups, but I don’t think any of those are exactly what you’re looking for.
Tasks can show totals for subtasks’ time-tracking fields, but not regular numeric fields.