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
auto_join=True, index=True, required=True,
        help="Location where the system will stock the finished products.")
    partner_id = fields.Many2one(
        'res.partner', 'Destination Address ',
        states={'done': [('readonly', True)]},
        help="Optional address where goods are to be delivered, specifically used for allotment")
    move_dest_ids = fields.Many2many(
        'stock.move', 'stock_move_move_rel', 'move_orig_id', 'move_dest_id', 'Destination Moves',
        copy=False,
        help="Optional: next stock move when chaining them")
    move_orig_ids = fields.Many2many(
        'stock.move', 'stock_move_move_rel', 'move_dest_id', 'move_orig_id', 'Original Move',
        copy=False,
        help="Optional: previous stock move when chaining them")
    picking_id = fields.Many2one('stock.picking', 'Transfer Reference', index=True, states={'done': [('readonly', True)]})
    picking_partner_id = fields.Many2one('res.partner', 'Transfer Destination Address', related='picking_id.partner_id')
    note = fields.Text('Notes')
    state = fields.Selection([
        ('draft', 'New'), ('cancel', 'Cancelled'),
        ('waiting', 'Waiting Another Move'),
        ('confirmed', 'Waiting Availability'),
        ('partially_available', 'Partially Available'),
        ('assigned', 'Available'),
        ('done', 'Done')], string='Status',
        copy=False, default='draft', index=True, readonly=True,
        help="* New: When the stock move is created and not yet confirmed.\n"
             "* Waiting Another Move: This state can be seen when a move is waiting for another one, for example in a chained flow.\n"
             "* Waiting Availability: This state is reached when the procurement resolution is not straight forward. It may need the scheduler to run, a component to be manufactured...\n"
             "* Available: When products are reserved, it is set to \'Available\'.\n"
             "* Done: When the shipment is processed, the state is \'Done\'.")