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
new_move = move._split(qty_split)
                for move_line in move.move_line_ids:
                    if move_line.product_qty and move_line.qty_done:
                        # 
                        # 
                        # 
                        try:
                            move_line.write({'product_uom_qty': move_line.qty_done})
                        except UserError:
                            pass
                # 
                move.move_line_ids.filtered(lambda x: x.qty_done == 0.0).write({'move_id': new_move})
            move.move_line_ids._action_done()
        # 
        # 
        for result_package in moves_todo\
                .mapped('move_line_ids.result_package_id')\
                .filtered(lambda p: p.quant_ids and len(p.quant_ids) > 1):
            if len(result_package.quant_ids.mapped('location_id')) > 1:
                raise UserError(_('You should not put the contents of a package in different locations.'))
        picking = moves_todo and moves_todo[0].picking_id or False
        moves_todo.write({'state': 'done', 'date': fields.Datetime.now()})
        moves_todo.mapped('move_dest_ids')._action_assign()
        # 
        if all(move_todo.scrapped for move_todo in moves_todo):
            return moves_todo
        if picking:
            picking._create_backorder()
        return moves_todo
    def unlink(self):