How to set the LMS status to Completed or Failed

Is there any reason preventing you from using SCORM 2004 to accomplish your task? 
SCORM 1.2 offers a single value (cmi.core.lesson_status) to store course statuses (passed, completed, failed, incomplete, browsed, not attempted). SCORM 2004 is able to report both the Completed and Passed success verbs simultaneously, and separates completion and success statuses (cmi.completion_status can be set to completed, incomplete, not attempted, unknown; cmi.success_status can be set to passed, failed, unknown). 

Possible solution with SCORM 1.2:
1.  LMS Reporting Passed/Failed
2. Tracking Options: Complete course trigger
3. Place a button on both Success and Failure layers
    a) Success layer triggers in this order: Complete course as Completed/Passed when the user clicks button, and Exit course when the user clicks button
    b) Failure layer triggers in this order: Complete course as Incomplete/Failed when the user clicks button, and Exit course when the user clicks button
This will result in Incomplete completion status and Unknown success status as long as the quiz is failed, and Complete completion status, and Passed success status if the quiz is passed. The only downside of this solution is that you have to force the learner to click on Exit button on the Result slide so these values are properly recorded. You may test this with or without the Exit button to note the difference. Otherwise, I strongly recommend SCORM 2004.