How to Charge Sales Tax on an Invoice

1). Enter the items purchased in the first section of the invoice. List each item's price toward the right side. For instance, a restaurant invoice might read: "Pie @ $2.00" and under that, "Coke @ $1.00" and under that "Meatballs @ $5.00."
2). Add a subtotal after all items have been entered. The subtotal is the combined total of all items. In the example from Step 1, the total for the pie, coke and meatballs is $8.00.
3). Enter an amount for the sales tax rate in your state. For instance, Wisconsin's sales tax is five percent (.05), so the sales tax rate will be multiplied by the subtotal to find the sales tax. For instance, $8.00 x .05 = $0.45. The 45 cents is entered as the sales tax.
4). If your invoice includes a blank space for a voluntary, non-taxable tip, add another subtotal line beneath the sales tax line. If a tip is mandatory it will be subject to sales tax, so you'll add the tip to your subtotal before the sales tax is calculated.
5). The last entry on the invoice is the total. This will include the subtotal after sales tax, plus any tip that is added by the customer.