After integrating NumberFormatter with more call sites, I'm convinced that it might be an okay idea after all to put the RoundingMode on the top level. That is, instead of:
you would do:
For example, I've seen call sites where they have a policy to always do half-up rounding, but the number of fraction digits is variable, and the combined rounder with rounding mode is not very appropriate for that use case.
This change would also affect skeleton syntax, so we need to decide soon.
It would also drastically reduce the number of overloads needed for a potential method-based C API.