SSAS - Preserve Measure Null Values

Generally when designing a data warehouse (at least in my experience) you don't think about NULL values appearing often in measure data of a fact table. You may have unknown foreign keys from your dimension data but even those unknown foreign keys relate to some kind of fact data. If you're new to data warehousing measure data would be things like price, quantity, duration. These are usually the business numbers that you want to aggregate in your cube.