My students write their answers to their multiple choice questions on the text booklet as well as the scantron. I return the booklet to them for review, with a copy of their scantron. I keep the original in case they would be tempted to change answers. They have 15 minutes to look over their test. If they question the scoring, they can write, on their booket, their defenses of their answers. I review them and make changes in grades if they convince me that I was wrong. Then I email each with my thoughts.
I also am available for individual review of tests, if the 15 minutes isn't enough.
I don't discuss tests with the group.
This has worked very well for me, for lots of years.