Sales tax is not calculating correctly

I know this process hasn't been easy for you, purecomputersonline. Let's work together to find a solution. 

We can review your group tax to confirm whether we have correctly configured the tax rate. 

If everything is correct and the issue still persists, your company file may have suffered some data damage. Not to worry, we can repair your company file using the Rebuild Data tool.

Beforehand, make sure QuickBooks is updated. This way, you'll have the latest features and fixes.

To verify the data: 

1. On the top menu, click File and select Utilities.
2. Click on Verify Data.
3. Select OK when QuickBooks doesn't detect any problem with your data.
4. If Verify finds an issue with your data, you'll be prompted to Rebuild Now or View Errors.
5. Click Close or View Errors and take note of the specific error message.

Next, here's how to rebuild data: 

1. On the top menu, click File and choose Utilities.
2. Click OK if you receive a prompt to back up your company file.
3. Select OK when the rebuild is complete.
4. You can rerun the Rebuild Data to ensure there's no error.

In case the issue persists,  use the QuickBooks File Doctor to fix your company file. 

Additionally, several sales reports in QBDT provide insights and analysis related to the company's sales activities. These reports can be customized according to your business needs.

Please update us if you need additional assistance managing your sales taxes in QuickBooks. We're always here to help you out.

This is normal. It happens because each tax within the tax group is calculated individually, rounded to the nearest cent, and stored as an individual line item, much like the line item rows you put on the invoice table.

In your case, the two .5% taxes have a 1/2 cent result, which is then rounded up for both of them, to the next full cent:

In the case above, if you used one 10% tax item instead of a group you'll get the expected amount, 2.50.

However, this is all a factor of the taxable amount and the individual tax rates, and where they fall before they are rounded, which will determine of the parts of cents are rounded up or down.

For example, if your taxable amount was 24.75, then the tax total also has to be rounded.  So, if you use a single 10% tax or the three in the group, you will get the same tax result, 2.48:

And, consider this case.  Here the totals are exactly the same, because there is 1/4 of a cent on the first tax, which is rounded down, and 3/4 of a cent on the second tax, which is rounded up:

@LeizylM  RE: If everything is correct and the issue still persists, your company file may have suffered some data damage

That's total nonsense.

If you had tried it yourself you would see that you get the same exact result as the OP. Every time in every file everywhere in every QuickBooks version year for about the last 30 years.

It's how QuickBooks works, which you would know had you actually bothered to check.