Round Commerce Price: in tpl.php or template.php
A better way to adjust currency formatting, using the relevant Commerce currency hooks, is with 

hook_commerce_currency_info_alter

and adding your own commerce_currency_format handler

e.g:

/**
 * hook_commerce_currency_info_alter
 * 
 * Add custom currency format to selected currencies
 */
function MY_MODULE_commerce_currency_info_alter(&amp;$currencies){
  $currencies['IDR']['format_callback'] = 'MY_MODULE_commerce_currency_format';
}

/**
 * Currency format callback
 *
 * Remove decimal places from output
 * while keeping commerce_amount_to_decimal formatting the same
 *
 * See: commerce_currency_format
 */
function MY_MODULE_commerce_currency_format($amount, $currency, $object = NULL, $convert = TRUE) {

  // Format the price as a number.
  // In our case, we remove decimal places
  $price = number_format(commerce_currency_round(abs($amount), $currency), 0, $currency['decimal_separator'], $currency['thousands_separator']);

  // Establish the replacement values to format this price for its currency.
  $replacements = array(
    '@code_before' =&gt; $currency['code_placement'] == 'before' ? $currency['code'] : '',
    '@symbol_before' =&gt; $currency['symbol_placement'] == 'before' ? $currency['symbol'] : '',
    '@price' =&gt; $price,
    '@symbol_after' =&gt; $currency['symbol_placement'] == 'after' ? $currency['symbol'] : '',
    '@code_after' =&gt; $currency['code_placement'] == 'after' ? $currency['code'] : '',
    '@negative' =&gt; $amount &lt; 0 ? '-' : '',
    '@symbol_spacer' =&gt; $currency['symbol_spacer'],
    '@code_spacer' =&gt; $currency['code_spacer'],
  );

  return trim(t('@code_before@code_spacer@negative@symbol_before@price@symbol_spacer@symbol_after@code_spacer@code_after', $replacements));
}