gistfile1.php

<?php
function elbe_current_user_can($capability, $current_user) {
	//replace wp2_ with your database prefix -.-
	$roles = get_option('wp2_user_roles');
	$user_roles = $current_user->wp_capabilities;
	if ($user_roles == null)
		return false;
	$user_roles = array_keys($user_roles, true);
	$role = $user_roles[0];
	$capabilities = $roles[$role]['capabilities'];
	if ( in_array( $capability, array_keys( $capabilities, true) ) ) {
		return true;
	}
}

//...

//in theme logic somewhere
if (elbe_current_user_can('discount',$current_user))
	//do something
?>