Mutt,
The FAA issues to operators relief to the 10% rule by way of either B043 or B044 Operation Specifications. Titled Planned Redispatch or Rerelease Enroute - they allow an operator to dispatch intially to an intermediate airport with the 121.645 required fuel with a plan to redispatch the flight enroute to the plan destination airport. The redispatch release must also contain the fuel required by 121.645 from the re-release point to destination. The gross impact is that you only carry the 10% fuel required from the re-release point to destination.
Your POI should be able to get you a copy of the OpSpec.