Create rule action to calculate tax on product field

In some cases it could come in handy if we could do calculations with rules on a price field instead of a line-item.
I made a custom rule for that purpose, maybe it comes in handy for anyone.

/**
 * Implementation of hook_rules_action_info().
 */
function MYMODULE_rules_action_info() {
  return array(
 'MYMODULE_calculate_vat' => array(
      'label' => t('Calculate VAT on a price field'),
      'parameter' => array(
        'commerce_price' => array(
          'type' => 'commerce_price',
          'label' => t('Price field without VAT'),
        ),
        'vat_rate_name' => array(
          'type' => 'text',
          'label' => t('vat rate'),
          'options list' => 'commerce_vat_rate_titles',
        ),
      ),
      'provides' => array(
        'applied_vat' => array(
          'type' => 'commerce_price',
          'label' => t('Price inclusive VAT'),
        ),
      ),
      'group' => t('Commerce VAT'),
      'callbacks' => array(
        'execute' => 'MYMODULE_commerce_vat_rate_rules_calculate_apply',
      ),
    ),
    
  );
}



/**
 * Applies a vat rate to the base price of a price field.
 *
 * @param $vat_rate
 *   The vat rate to apply to the line item.
 * @param $commerce_price
 *   The field whose base price will be modified to include the vat.
 *
 * @return
 *   A price array representing the vat applied to the line item or FALSE if
 *   none was applied.
 */
function MYMODULE_commerce_vat_rate_rules_calculate_apply($commerce_price, $vat_rate) {
  if ($vat_rate = commerce_vat_rate_load($vat_rate)) {
    foreach ($vat_rate['rates'] as $rate) {
      if (strtotime($rate['start']) < time()) {
        $rate_info = $rate;
        break;
        }
      }
    // If a valid rate is specified...
    if (isset($rate_info['rate']) && is_numeric($rate_info['rate'])) {
      
      // Don't apply vat if the unit price has a NULL amount.
      if (is_null($commerce_price['amount'])) {
        return;
        }
        
      //Todo: load the data for the field to pay respect to the rounded options
      // If the price has been rounded up take the half off before calculating VAT
      if (isset($data['rounded_up']) && $data['rounded_up']) {
        $commerce_price['amount'] = $commerce_price['amount'] - 0.5;
        }
      
      $commerce_price['amount'] = $commerce_price['amount'] * $rate_info['rate'];
      $commerce_price['amount'] = commerce_vat_rate_round_amount($commerce_price['amount']);
      
      return array('applied_vat' => $commerce_price);
      }
    return FALSE;
    }
  return FALSE;
  }