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
if any(move.state not in ('draft', 'cancel') for move in self):
            raise UserError(_('You can only delete draft moves.'))
        # 
        self.mapped('move_line_ids').unlink()
        return super(StockMove, self).unlink()
    def _prepare_move_split_vals(self, qty):
        vals = {
            'product_uom_qty': qty,
            'procure_method': 'make_to_stock',
            'move_dest_ids': [(4, x.id) for x in self.move_dest_ids if x.state not in ('done', 'cancel')],
            'move_orig_ids': [(4, x.id) for x in self.move_orig_ids],
            'origin_returned_move_id': self.origin_returned_move_id.id,
            'price_unit': self.price_unit,
        }
        if self.env.context.get('force_split_uom_id'):
            vals['product_uom'] = self.env.context['force_split_uom_id']
        return vals
    def _split(self, qty, restrict_partner_id=False):