The sales journal is a list of client invoices (sales) but on the Income Statement all forms of revenue are accounted for. There are two possible scenarios that would cause total sales figure on the Sales Journal not to match the Total Revenue on the Income Statement.
The first is accounts affected by the Sales Journal that are not listed in the revenue section of the income statement. To find these, use the Account Summary section of the Sales Journal and look up the type of each account in your chart of accounts. You will need to deduct any amounts for accounts that are not revenue (i.e. There may be certain credits, returns, commissions, etc that invoices are done for and go into a COGS or expense account?sales tax is also not revenue).
In turn you also need to look for entries posted to a revenue type accounts that are not listed on the Sales Journal. This is because the Sales Journal only shows client invoices (or sales) but your revenue can be affected by interest earned, insurance refunds, commissions, credits, bad debt, etc. all of which would come into the system as a type other than a client invoice such as a miscellaneous cash receipt. To do this you will need to run an Account Inquiry Report for your range of revenue accounts and look for entries that are not related to client invoices such as operating expenses, misc. cash, or journal entries. Since the Account Inquiry Report lists transactions in type order these transactions should appear at the beginning or end of each account transaction listing.