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
quantity_done = self[0].quantity_done  
        for move in self:
            move_lines = move._get_move_lines()
            if not move_lines:
                if quantity_done:
                    
                    move_line = self.env['stock.move.line'].create(dict(move._prepare_move_line_vals(), qty_done=quantity_done))
                    move.write({'move_line_ids': [(4, move_line.id)]})
            elif len(move_lines) == 1:
                move_lines[0].qty_done = quantity_done
            else:
                raise UserError("Cannot set the done quantity from this stock move, work directly with the move lines.")
    def _set_product_qty(self):
        """ The meaning of product_qty field changed lately and is now a functional field computing the quantity
        in the default product UoM. This code has been added to raise an error if a write is made given a value
        for `product_qty`, where the same write should set the `product_uom_qty` field instead, in order to
        detect errors. """
        raise UserError(_('The requested operation cannot be processed because of a programming error setting the `product_qty` field instead of the `product_uom_qty`.'))
    @api.multi
    @api.depends('move_line_ids.product_qty')
    def _compute_reserved_availability(self):