Hi, Candace!
Since the Total column isn't in the actual data table from which the report is generated, then I don't believe it's possible to include it in the filters area of the report editor. You can still filter on values in that column, but it will need to be done manually when you view the report. Using your example, in report view mode, try putting >=4&&<=6 in the filter bar above the Total column. I believe this will filter the table on only rows where the Total value is 4, 5, or 6.