It's not clear whether you are adding up the box 8 amounts on the actual 1099-INT forms, or the amounts in TurboTax. If you are looking at the forms, double-check the entries in TurboTax. See if you made a mistake entering one of the amounts.
If you are using the CD/Download TurboTax software, you can open Schedule B in forms mode to see a list of the amounts that were entered. You can also look at the individual Form 1099-INT Worksheets.
