multi_store_pos/security/multi_store_security.xml

<?xml version="1.0"?>
<openerp>
    <data noupdate="1">
        <record id="pos_config_store_rule" model="ir.rule">
            <field name="name">Pos Config multi-store</field>
            <field name="model_id" ref="point_of_sale.model_pos_config"/>
            <field name="global" eval="True"/>
            <field name="domain_force">['|',('journal_id.store_ids','=',False),('journal_id.store_ids','child_of',[user.store_id.id])]</field>
        </record>

        <record id="pos_order_store_rule" model="ir.rule">
            <field name="name">Pos Order multi-store</field>
            <field name="model_id" ref="point_of_sale.model_pos_order"/>
            <field name="global" eval="True"/>
            <field name="domain_force">['|',('sale_journal.store_ids','=',False),('sale_journal.store_ids','child_of',[user.store_id.id])]</field>
        </record>

        <record id="pos_session_store_rule" model="ir.rule">
            <field name="name">Pos Session multi-store</field>
            <field name="model_id" ref="point_of_sale.model_pos_session"/>
            <field name="global" eval="True"/>
            <field name="domain_force">['|',('config_id.journal_id.store_ids','=',False),('config_id.journal_id.store_ids','child_of',[user.store_id.id])]</field>
        </record>
    </data>
</openerp>