public function findAll()
    {

        // initialize the array with the available tax classes
        $taxClasses = array();

        // execute the prepared statement
        $this->taxClassesStmt->execute();

        // load the available tax classes
        $availableTaxClasses = $this->taxClassesStmt->fetchAll();

        // fetch the tax classes and assemble them as array with the class name as key
        foreach ($availableTaxClasses as $taxClass) {
            $taxClasses[$taxClass[MemberNames::CLASS_NAME]] = $taxClass;
        }

        // return the array with the tax classes
        return $taxClasses;
    }