pos/pos_pricelist/security/account_fiscal_position_security.xml

<?xml version="1.0" encoding="utf-8"?>

<openerp>
<data noupdate="1">

    <record id="account_fiscal_position_tax_multi_company_rule" model="ir.rule">
        <field name="name">Account fiscal position tax multi-company</field>
        <field name="model_id" ref="model_account_fiscal_position_tax"/>
        <field name="domain_force">['|', ('company_id', '=', False), ('company_id', 'child_of', [user.company_id.id])]</field>
    </record>

</data>
</openerp>