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
extra_move_quantity -= extra_move_quantity
                    if extra_move_quantity == 0.0:
                        break
        return extra_move
    def _action_done(self):
        self.filtered(lambda move: move.state == 'draft')._action_confirm()  # 
        moves = self.filtered(lambda x: x.state not in ('done', 'cancel'))
        moves_todo = self.env['stock.move']
        # 
        # 
        for move in moves:
            if move.quantity_done <= 0:
                if float_compare(move.product_uom_qty, 0.0, precision_rounding=move.product_uom.rounding) == 0:
                    move._action_cancel()
        # 
        for move in moves:
            if move.state == 'cancel' or move.quantity_done <= 0:
                continue
            # 
            if not move.picking_id:
                moves_todo |= move
            moves_todo |= move._create_extra_move()
        # 
        for move in moves_todo:
            # 
            # 
            rounding = self.env['decimal.precision'].precision_get('Product Unit of Measure')
            if float_compare(move.quantity_done, move.product_uom_qty, precision_digits=rounding) < 0:
                # 
                qty_split = move.product_uom._compute_quantity(move.product_uom_qty - move.quantity_done, move.product_id.uom_id, rounding_method='HALF-UP')