Yes! With a ShipStation trial, you can view these USPS rates through Stamps.com within the Rate Calculator, when creating labels, and when making a test label. The rates you see in these will be the rates you will receive if you sign up for a Single Account Solution on Stamps.com through ShipStation.
To sign up for a Stamps.com account, simply click on a Create Label button anywhere within the interface. This can be done on the Rate Calculator or in the Ship Label modal.
Here's how this process will look:
On the popup that appears, click Add Funds and Create Label.
Now, you'll be able to create a test label to see how the label looks or you can go on and set up a Stamps.com account.
When setting up a Stamps.com account, choose if this is a new account or an existing Stamps.com account then click Next.
On the new popup that appears, fill out the information and you'll be ready to get ship done as soon as you click Create Free Account!
THINGS TO KEEP IN MIND:
As long as you have an active ShipStation account, this Stamps.com account's monthly fees will be covered.
If you have an existing Stamps.com account, you can attach it by selecting I already have a Stamps.com account. If this account is not a specialized account with negotiated rates, you will be able to have your Stamps.com account converted to the $0 per month Stamps.com plan.
If your existing Stamps.com account contains negotiated rates, though, you will be able to configure the settings on the connected Stamps.com account to use your specific rate table.