If you must have that kind of resolution, look into Denver scales. I use TR-104 for powder weighing and TL-602 for bullet sorting.
TR-104 has .001 grain resolution, which is far too fine for reloading.
After many chrono sessions, I could never correlate better than a tenth-grain powder consistency to an improved SD or any other reload consistency measurement.
Summary: don't bother. Any good digital scale is adequate for reloading. I recommend PACT or Dillon's.
LT