Change text

change_my_text_example.php

<?php

// Add this code below to your PMPro Customizations plugin - http://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/

add_filter( 'gettext', 'change_my_text_example', 20, 3 );
/**
 * @link http://codex.wordpress.org/Plugin_API/Filter_Reference/gettext
 */
function change_my_text_example( $translated_text, $text, $domain ) {  

        switch ( $translated_text ) {

            case "Tax" :

                $translated_text = __( 'GST', 'paid-memberships-pro' );
                break;
        }

    return $translated_text;
}