Alter the currency display in WooCommerce.

functions.php

/**
 * Change currency display in WooCommerce
 * Put this in your functions.php file
 */
function softiconic_currency_symbol( $currency_symbol, $currency ) {
    switch( $currency ) {
        case 'USD':
            $currency_symbol = 'USD $';
            break;
        case 'CAD':
            $currency_symbol = 'CAD $';
            break; 
    }
    return $currency_symbol;
}
add_filter('woocommerce_currency_symbol', 'softiconic_currency_symbol', 30, 2);