Precision level filter responsibility?

I'm wondering if limit precision should be managed in the spec with a filter like 'precision=6' or should be kept at data file/store behind the web service or both.

This viewpoint comes from 2 main reasons:

• Sending ten digits precision has no meaning: see this summary https://gis.stackexchange.com/a/8674
• The cost of geometry precision: for WGS 84, each coordinates with 10 digit precision would cost around 30% of the geometry size

Geometry with 6 digits (10 characters)

179.999999

Geometry with 10 digits (14 characters)

179.999999999

For point geometry, the gain is small but for lines and polygones, the improvement would be worth for the response size.

The other question it would open is about rounding or cutting for this precision, if considered in the core spec.