Type 'sales tax' in the Search window, then 'Jump to sales tax'.
You should see a screen titled "Let's Compare Your Sales Tax and Income Tax". Choose Try Sales Tax and Continue.
On the next screen "How do you want to Enter your Sales Tax Info?" choose Easy Guide and Continue.
The next screen "Places You Lived" will give you a choice to Edit your previous entry to add a major purchase, change the tax rate or location.
Or, you can Delete your previous entry and start a new entry.