Impacted versions:

[9.0]
Tested in runbot http://174550-9-0-10dcec.runbot10.odoo.com/

Steps to reproduce:

Set the Tax Calculation Rounding Method to "Round Globally" 
Create a Sales Order with the following lines with 7% taxes

1) 5,095.20 
2) 523.20 
3) 80.64 
4) 54.12 
5) 182.00 
6) 186.20 
![image](https://cloud.githubusercontent.com/assets/16055718/19144073/309aa082-8bda-11e6-81d0-2461c4e9a467.png)

Create a Sales Invoice with the same lines with 7% taxes
![image](https://cloud.githubusercontent.com/assets/16055718/19144078/38048b58-8bda-11e6-9c2b-4b501cfa1e12.png)

Current behavior:

The total taxes in Sales Order are $477.48 

The total taxes in Sales Invoice are $477.50 

Expected behavior:

Both the total taxes in Sales Order and Sales Invoice should be 477.50 

Video/Screenshot link (optional):

for line in self:
            line.qty_delivered_updateable = line.product_id.invoice_policy in ('order', 'delivery') and line.order_id.state == 'sale' and line.product_id.track_service == 'manual'
    @api.depends('qty_invoiced', 'qty_delivered', 'product_uom_qty', 'order_id.state')
    def _get_to_invoice_qty(self):
        """
        Compute the quantity to invoice. If the invoice policy is order, the quantity to invoice is
        calculated from the ordered quantity. Otherwise, the quantity delivered is used.
        """
        for line in self:
            if line.order_id.state in ['sale', 'done']:
                if line.product_id.invoice_policy == 'order':
                    line.qty_to_invoice = line.product_uom_qty - line.qty_invoiced
                else:
                    line.qty_to_invoice = line.qty_delivered - line.qty_invoiced
            else:
                line.qty_to_invoice = 0
    @api.depends('invoice_lines.invoice_id.state', 'invoice_lines.quantity')
    def _get_invoice_qty(self):