WooCommerce Currency Symbol

I found it to be very easy. Just insert the following code block to functions.php file under theme folder.

//Change the symbol of an existing currency
add_filter('woocommerce_currency_symbol', 'change_existing_currency_symbol', 10, 2);
     switch( $currency ) {
          case 'USD': $currency_symbol = 'USD$'; break;
}
     return $currency_symbol;
}