If you don't need to track cash sales for each customer, you can record all your cash sales for a specific period of time on a single cash sales receipt. The cash sales receipt acts as a summary of your sales for that period of time.
You must create a new sales summary template that reflects the new price. When you memorize the new template, save it under the name you chose for the original template. QuickBooks will then replace the original template with the new template.