pos/pos_product_template/view/view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- ********************************************************************** -->
<!--Point Of Sale - Product Template module for Odoo                        -->
<!--Copyright (C) 2014-Today Akretion (http://www.akretion.com)             -->
<!--@author Sylvain LE GAL (https://twitter.com/legalsylvain)               -->

<!--This program is free software: you can redistribute it and/or modify    -->
<!--it under the terms of the GNU Affero General Public License as          -->
<!--published by the Free Software Foundation, either version 3 of the      -->
<!--License, or (at your option) any later version.                         -->

<!--This program is distributed in the hope that it will be useful,         -->
<!--but WITHOUT ANY WARRANTY; without even the implied warranty of          -->
<!--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           -->
<!--GNU Affero General Public License for more details.                     -->

<!--You should have received a copy of the GNU Affero General Public License-->
<!--along with this program.  If not, see <http://www.gnu.org/licenses/>.   -->
<!-- ********************************************************************** -->
<openerp>
    <data>
<!-- Add: JS Files -->
        <template id="assets_backend" name="point_of_sale assets2" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/pos_product_template/static/src/js/ppt.js"></script>
            </xpath>
        </template>

<!-- Add: CSS Files -->
<template id="index" name="pos_product_template index" inherit_id="point_of_sale.index">
    <xpath expr="//link[@id='pos-stylesheet']" position="after">
        <link rel="stylesheet" href="/pos_product_template/static/src/css/ppt.css" id="pos_product_template-stylesheet"/>
    </xpath>
</template>

    </data>
</openerp>