[ADD] PoS: add new Cash Rounding documentation (#484)

point_of_sale/advanced.rst

@@ -8,4 +8,5 @@ Advanced topics
    advanced/barcode
    advanced/multicashiers
    advanced/reprint
-   advanced/mercury
+   advanced/mercury
+   advanced/cash_rounding

point_of_sale/advanced/cash_rounding.rst

@@ -0,0 +1,50 @@
+=============
+Cash Rounding
+=============
+**Cash rounding** is required when the lowest physical denomination 
+of currency, or the smallest coin, is higher than the minimum unit 
+of account.
+
+For example, some countries require their companies to round up or 
+down the total amount of an invoice to the nearest five cents, when 
+the payment is made in cash.
+
+Each point of sale in Odoo can be configured to apply cash rounding
+to the totals of its bills or receipts. 
+
+.. note::
+   This feature will soon be added to Odoo. We are currently working
+   to make it available for all supported versions as soon as possible.
+
+Configuration
+=============
+Go to :menuselection:`Point of Sale --> Configuration --> Settings` 
+and enable *Cash Rounding*, then click on *Save*.
+
+.. image:: media/cash_rounding01.png
+    :align: center
+
+Go to :menuselection:`Point of Sale --> Configuration --> Point of 
+Sale`, open the point of sale you want to configure, and enable the
+*Cash Rounding* option.
+
+To define the **Rounding Method**, open the drop-down list and click
+on *Create and Edit...*.
+
+Define here your *Rounding Precision*, *Profit Account*, and 
+*Loss Account*, then save both the Rounding Method and your Point
+of Sale settings.
+
+.. image:: media/cash_rounding02.png
+    :align: center
+
+All total amounts of this point of sale now add a line to apply the
+rounding according to your settings.
+
+.. image:: media/cash_rounding03.png
+    :align: center
+
+.. note::
+   Odoo Point of Sale only support the *Add a rounding line* 
+   rounding strategies and *Half-up* rounding methods. 
+