If I cancle my QB account, am I still able to access it for past sales and tax porposes?

Hi bigphilsrubbish, 

QuickBooks Online is designed to be as user-friendly as possible, and it's our goal to make sure you can take your business into your own hands. While we're sad to see you go, I know you have to make the choice that's best for your business. I'll explain what happens following the cancellation of your subscription. 

In order to cancel the account, you'll have to follow these steps:

1. Click the Gear icon. 
2. Select Account and Settings.

3. Click Billing and Subscription.

4. Click Cancel Subscription.

Once cancelled, you'll have 365 days of read-only access to your account. You'll be able to log into the account and view or export information, but you're unable to make any changes. After 365 days, the data will be permanently removed from our servers. 

I hope this helps.

Take care.