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
if move.move_dest_ids and move.propagate:
                    if 'date_expected' in propagated_changes_dict:
                        propagated_changes_dict.pop('date_expected')
                    if propagated_date_field:
                        current_date = datetime.strptime(move.date_expected, DEFAULT_SERVER_DATETIME_FORMAT)
                        new_date = datetime.strptime(vals.get(propagated_date_field), DEFAULT_SERVER_DATETIME_FORMAT)
                        delta = relativedelta.relativedelta(new_date, current_date)
                        if abs(delta.days) >= move.company_id.propagation_minimum_delta:
                            old_move_date = datetime.strptime(move.move_dest_ids[0].date_expected, DEFAULT_SERVER_DATETIME_FORMAT)
                            new_move_date = (old_move_date + relativedelta.relativedelta(days=delta.days or 0)).strftime(DEFAULT_SERVER_DATETIME_FORMAT)
                            propagated_changes_dict['date_expected'] = new_move_date
                    
                    
                    if propagated_changes_dict:
                        move.move_dest_ids.filtered(lambda m: m.state not in ('done', 'cancel')).write(propagated_changes_dict)
        track_pickings = not self._context.get('mail_notrack') and any(field in vals for field in ['state', 'picking_id', 'partially_available'])
        if track_pickings:
            to_track_picking_ids = set([move.picking_id.id for move in self if move.picking_id])
            if vals.get('picking_id'):
                to_track_picking_ids.add(vals['picking_id'])
            to_track_picking_ids = list(to_track_picking_ids)
            pickings = Picking.browse(to_track_picking_ids)
            initial_values = dict((picking.id, {'state': picking.state}) for picking in pickings)
        res = super(StockMove, self).write(vals)
        if track_pickings:
            pickings.message_track(pickings.fields_get(['state']), initial_values)
        if receipt_moves_to_reassign:
            receipt_moves_to_reassign._action_assign()
        return res
    def action_show_details(self):