https://github.com/odoo/odoo/blob/b192431aeecc59b48898ce9c6f276b82d65cbfa6/addons/stock/models/stock_move.py#L1026

rounding_method ='UP'
I think it **need be changed to:**
rounding_method ='HALF-UP'

I get this message then I Verify new Delivery(stock.picking):

> The initial demand has been updated.
> My Product
> Quantity : 5.951 -> 5.949999999999999 

and
> The initial demand has been updated.
> My Product
> Quantity : 5.951 -> 5.951 


How I did it(you can also repeat this error): Create new Product > add Qty on hand > Create SO > Add Product with quantity 5.5 > Verify > open Delivery > add Delivered qty 5.95 > Verify > Get trouble: odoo change my qty to 5.951
![default](https://user-images.githubusercontent.com/34191760/39213952-9b246470-481b-11e8-8e06-a074b1044536.png)

You can try execute in python:
5.95 - 5.5 = 0.4500000000000002

Look at the code:
```
            extra_move_quantity = float_round(
                self.quantity_done - self.product_uom_qty,
                precision_rounding=self.product_uom.rounding,
                rounding_method ='UP')
```
if you setup parameters like this:
```
            0.451 = float_round(
                5.95 - 5.5,
                precision_rounding=self.product_uom.rounding,
                rounding_method ='UP')
```
Then you get 0.451.  This is wrong!
Try:
```
            0.45 = float_round(
                5.95 - 5.5,
                precision_rounding=self.product_uom.rounding,
                rounding_method ='HALF-UP')
```
0.45 = 5.95 - 5.5
addons/stock/models/stock_move.py
res = []
        for move in self:
            res.append((move.id, '%s%s%s>%s' % (
                move.picking_id.origin and '%s/' % move.picking_id.origin or '',
                move.product_id.code and '%s: ' % move.product_id.code or '',
                move.location_id.name, move.location_dest_id.name)))
        return res
    @api.model
    def create(self, vals):
        
        perform_tracking = not self.env.context.get('mail_notrack') and vals.get('picking_id')
        if perform_tracking:
            picking = self.env['stock.picking'].browse(vals['picking_id'])
            initial_values = {picking.id: {'state': picking.state}}
        vals['ordered_qty'] = vals.get('product_uom_qty')
        res = super(StockMove, self).create(vals)
        if perform_tracking: