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
readonly=True, help='Quantity that has already been reserved for this move')
    availability = fields.Float(
        'Forecasted Quantity', compute='_compute_product_availability',
        readonly=True, help='Quantity in stock that can still be reserved for this move')
    string_availability_info = fields.Text(
        'Availability', compute='_compute_string_qty_information',
        readonly=True, help='Show various information on stock availability for this move')
    restrict_partner_id = fields.Many2one('res.partner', 'Owner ', help="Technical field used to depict a restriction on the ownership of quants to consider when marking this move as 'done'")
    route_ids = fields.Many2many('stock.location.route', 'stock_location_route_move', 'move_id', 'route_id', 'Destination route', help="Preferred route")
    warehouse_id = fields.Many2one('stock.warehouse', 'Warehouse', help="Technical field depicting the warehouse to consider for the route selection on the next procurement (if any).")
    has_tracking = fields.Selection(related='product_id.tracking', string='Product with Tracking')
    quantity_done = fields.Float('Quantity Done', compute='_quantity_done_compute', digits=dp.get_precision('Product Unit of Measure'), inverse='_quantity_done_set')
    show_operations = fields.Boolean(related='picking_id.picking_type_id.show_operations')
    show_details_visible = fields.Boolean('Details Visible', compute='_compute_show_details_visible')
    show_reserved_availability = fields.Boolean('From Supplier', compute='_compute_show_reserved_availability')
    picking_code = fields.Selection(related='picking_id.picking_type_id.code', readonly=True)
    product_type = fields.Selection(related='product_id.type', readonly=True)
    additional = fields.Boolean("Whether the move was added after the picking's confirmation", default=False)
    is_locked = fields.Boolean(compute='_compute_is_locked', readonly=True)
    is_initial_demand_editable = fields.Boolean('Is initial demand editable', compute='_compute_is_initial_demand_editable')
    is_quantity_done_editable = fields.Boolean('Is quantity done editable', compute='_compute_is_quantity_done_editable')
    reference = fields.Char(compute='_compute_reference', string="Reference", store=True)
    has_move_lines = fields.Boolean(compute='_compute_has_move_lines')
    @api.depends('picking_id.is_locked')
    def _compute_is_locked(self):
        for move in self:
            if move.picking_id:
                move.is_locked = move.picking_id.is_locked
    @api.depends('product_id', 'has_tracking', 'move_line_ids', 'location_id', 'location_dest_id')
    def _compute_show_details_visible(self):