Rounding assigned quantity
I think we have the same issue as https://github.com/odoo/odoo/commit/383947646f5652804bd6bbc764380a890e6f4a8d
The problem is that we round the quantity assigned:
http://hg.tryton.org/modules/stock/file/846866f11236/move.py#l937
http://hg.tryton.org/modules/stock/file/846866f11236/move.py#l946
This may result is losing precision if the UOM has high rounding value.
I think the solution would be to have on uom a method that returns the best uom to use to express a quantity. Of course, the uom should have the same category as the initial one and it should return the initial if there is not precision lost.
This method will be used to store the uom and quantity on the assigned moves.