It is possible to set up a quiz to be automatically graded and automatically posted to a gradebook item which can exceed the point value of the quiz. The method for achieving this outcome varies depending upon you are using a WEIGHTED or POINTS gradebook.
In a WEIGHTED Gradebook, the instructor must mark individual questions in the quiz itself as 'bonus.' Otherwise, the grade item will record the percentage of the quiz score rather than the point total.
For example, for a ten-question quiz worth 10 points (where no individual questions are designated as "bonus"), when the quiz is automatically graded and sent to a gradebook item worth 9 points (even with 'can exceed' marked), the highest score that will be recorded in the gradebook is 9. In this scenario, the gradebook will register that the quiz attempt was marked 100%, rather than 10 points.
To allow the attempt to register as more than 100% in the gradebook, at least one question or questions must be identified as "bonus." To do this, click the [Layout/Questions] area of the quiz, click on [Edit Values] and mark the question(s) that are bonus.
In a POINTS Gradebook, it is not necessary to mark any of the quiz questions as "bonus." The Instructor must simply be sure that the grade book Category is not marked to "distribute points evenly." This will allow the grade points to be exported from the quiz into the gradebook accurately, so that the grade item accurately exceeds both the allotted points (e.g., 22 vs. 20) and percentage (e.g., 22/20 points gets a percentage of 110%).