Welcome to the Community. I'm here to share some insights on why your income on your Profit & Loss doesn't match with your gross sales.
The total sales and total income will not always match because there are transactions that can appear in a data file that will make it unlikely for the Sales Tax Liability and Profit and Loss reports to match. You can compare the two reports to see which transactions are causing the discrepancies.
To fix the problem, compare the details of the totals by running the Sales Tax Liability report and the Profit & Loss report.
To do that:
Click on Reports at the left pane.
Select on SalesTaxLiabilityReport.
Choose the correct report basis.
Select the DateRange.
Click on RunReport.
Double-click the Tax amount to see the details of the transaction.
Once done, run the Profit & Loss report and do the same process. If the issue persists, I'd suggest giving our Customer Care Team a call. They have necessary tools such as screen sharing that will help you figure this out.