You can do the queries ROLLBACK WORK, BEGIN WORK, COMMIT WORK with a call to
ifx_query()
Below is an example of how I handle a rollback.
function failure_exit()
{
global $conn;
$exec = ifx_query("ROLLBACK WORK", $conn);
if(!$exec)
{
$err = ifx_errormsg();
HandleError("db","other","failure_exit():ifx_query(): 'ROLLBACK WORK' - $err", 0);
}
@ifx_close($conn);
exit();
}