In OpenERP first, create custom module than inherits the sale menu and pass the view_mode in your menu file, follow these steps show below

Step1- The first step is to create a module i.e test and then create a file test.py and in this file, create an object in your module.

Use this code given below

from dateutil.relativedelta import relativedelta
from openerp import api,models,_
from openerp.osv import osv, fields
class test(osv.osv):
    _name = 'test'
    _rec_name = 'reference'
    _columns = {
                 'invoice_total_paid' : fields.function("Total Amount"),
                }
test()

Step2- Then create, another file i.e as test.xml file in your test module and create a view for your module.

Use this code show in below

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
 <!--  Here is a test order tree view -->   
      <record model="ir.ui.view" id="test_order_tree_view">
            <field name="name">test.order.tree.view</field>
            <field name="model">test</field>
            <field name="type">tree</field>
            <field name="arch" type="xml">
                <tree string="test Orders">
                    <field name="invoice_total_paid"/>
                 </tree>
            </field>
      </record>

<!--  Here is a test order tree view --> 

      <record model="ir.ui.view" id="test_order_form_view">
            <field name="name">rent.order.form.view</field>
            <field name="model">rent.order</field>
            <field name="type">form</field>
            <field name="arch" type="xml">
                <form string="Rent Order">
                    <group colspan="4" col="6">
                        <field name="invoice_total_paid"/> 
                    </group>
                 </form>
              </field>
       </record>
   </data>
</openerp>

Step3- Then we create another file i.e as menus.xml file in your test module and pass views id in this file and also create a menu in this file.

Use this code show in below

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <!--
            Basic Menu (Sales->Sale Orders)
        -->
        <record model="ir.actions.act_window" id="test_action_form">
            <field name="name">test Order</field>
            <field name="res_model">test</field>
            <field name="view_type">form</field>
            <field name="view_mode">tree,form</field>
            <field name="usage">menu</field>
            <field name="search_view_id" ref="test_order_form_view"/>
        </record>
        <menuitem id="rent_order_menu" parent="base.menu_sales" groups="base.group_sale_salesman"
                  name="test Orders" action="test_action_form"/>  
   </data>                
</openerp>