Can I print/save supporting forms in Turbo Tax Deluxe such as Interest & Dividends, etc.?

Yes.  Try printing from the Print Center

Log back in your TurboTax account and "add a state" to open the return back up (you are not really adding a state, just to open it back up), then

Click on Tax Tools on the left side of the online program screen. 

Then click on Print Center. 

Then click on Print, save or preview this year's return.  Choose the option Include government and TurboTax worksheets

See this answer on how to open your return and print all the worksheets.  It has a screen shot.

https://ttlc.intuit.com/community/state-taxes/discussion/print-out/00/815498

Even if you imported the info off a W-2, 1099-B, 1099-INT or DIV, etc ... the program doesn't have the forms ... just the info you entered or was imported listed on the worksheets.  

You can locate the worksheets that were included in your tax return by accessing a complete copy of your tax return from the Print Center. The PDF file of your tax return that is located on the tax home page will not include the worksheets.  Please note: this may not work until your return has been accepted.

Please take the steps below to obtain a complete copy of your tax return which would include all worksheets:

1. Sign in to your account (if you haven't already done so), using the samelogin you used to file your return.
2. Scroll down to My Tax Returns and Documents and click on show.
3. Next scroll down and click on Add a State (you are not really adding a state, this will allow you to get back into the program.)
4. In the left side panel click on Tax Tools then click on Print Center.
5. Next select Print, save or preview this year's return.
6. Then select the option to print your 2018 federal and state returns(shortest version). You can also select the option to Include government worksheets (optional) (medium-length version) and/or You can also select Include government and TurboTax worksheets (optional) (longest version). Then select View or print forms.
7. This will allow you to print your complete tax file.