To Use amount booked in the company currency in openerp Follow these step to given below
Step-1 Install the account_voucher module.
Step-2 After that custmozie account_voucher module.
In below example, I have custmozied account_voucher module. You can directly use the below account_voucher module in your addons.

res['amount_original'] = currency_pool.compute(cr, uid, company_currency, voucher_currency, move_line.credit or move_line.debit or 0.0, context=ctx) 
                res['amount_unreconciled'] = currency_pool.compute(cr, uid, company_currency, voucher_currency, abs(move_line.amount_residual), context=ctx)
        rs_data[line.id] = res 
    return rs_data 

def _currency_id(self, cr, uid, ids, name, args, context=None): 
    ''' 
    This function returns the currency id of a voucher line. It's either the currency of the 
    associated move line (if any) or the currency of the voucher or the company currency. 
    ''' 
    res = {} 
    for line in self.browse(cr, uid, ids, context=context): 
        move_line = line.move_line_id 
        if move_line: 
            res[line.id] = move_line.currency_id and move_line.currency_id.id or move_line.company_id.currency_id.id 
        else: 
            res[line.id] = line.voucher_id.currency_id and line.voucher_id.currency_id.id or line.voucher_id.company_id.currency_id.id 
    return res 

_columns = { 
    'voucher_id':fields.many2one('account.voucher', 'Voucher', required=1, ondelete='cascade'), 
    'name':fields.char('Description', size=256), 
    'account_id':fields.many2one('account.account','Account', required=True), 
    'partner_id':fields.related('voucher_id', 'partner_id', type='many2one', relation='res.partner', string='Partner'), 
    'untax_amount':fields.float('Untax Amount'), 
    'amount':fields.float('Amount', digits_compute=dp.get_precision('Account')), 
    'reconcile': fields.boolean('Full Reconcile'), 
    'type':fields.selection([('dr','Debit'),('cr','Credit')], 'Dr/Cr'), 
    'account_analytic_id':  fields.many2one('account.analytic.account', 'Analytic Account'), 
    'move_line_id': fields.many2one('account.move.line', 'Journal Item'), 
    'date_original': fields.related('move_line_id','date', type='date', relation='account.move.line', string='Date', readonly=1), 
    'date_due': fields.related('move_line_id','date_maturity', type='date', relation='account.move.line', string='Due Date', readonly=1), 
    'amount_original': fields.function(_compute_balance, multi='dc', type='float', string='Original Amount', store=True, digits_compute=dp.get_precision('Account')), 
    'amount_unreconciled': fields.function(_compute_balance, multi='dc', type='float', string='Open Balance', store=True, digits_compute=dp.get_precision('Account')), 
    'company_id': fields.related('voucher_id','company_id', relation='res.company', type='many2one', string='Company', store=True, readonly=True), 
    'currency_id': fields.function(_currency_id, string='Currency', type='many2one', relation='res.currency', readonly=True), 
} 
_defaults = { 
    'name': '', 
} 

def onchange_reconcile(self, cr, uid, ids, reconcile, amount, amount_unreconciled, context=None): 
    vals = {'amount': 0.0} 
    if reconcile: 
        vals = { 'amount': amount_unreconciled} 
    return {'value': vals} 

def onchange_amount(self, cr, uid, ids, amount, amount_unreconciled, context=None): 
    vals = {} 
    if amount: 
        vals['reconcile'] = (amount == amount_unreconciled) 
    return {'value': vals} 

def onchange_move_line_id(self, cr, user, ids, move_line_id, context=None): 
    """ 
    Returns a dict that contains new values and context 

    @param move_line_id: latest value from user input for field move_line_id 
    @param args: other arguments 
    @param context: context arguments, like lang, time zone 

    @return: Returns a dict which contains new values, and context 
    """ 
    res = {} 
    move_line_pool = self.pool.get('account.move.line') 
    if move_line_id: 
        move_line = move_line_pool.browse(cr, user, move_line_id, context=context) 
        if move_line.credit: 
            ttype = 'dr' 
        else: 
            ttype = 'cr' 
        res.update({ 
            'account_id': move_line.account_id.id, 
            'type': ttype, 
            'currency_id': move_line.currency_id and move_line.currency_id.id or move_line.company_id.currency_id.id, 
        }) 
    return { 
        'value':res, 
    }