Yes, you can show a banner to a customer who has some specific tag.

Follow the below steps to set up.
Open the Shipping Bar App and click on the "Edit" button for which you want to change Currency.

Go to the setting tab check the "Enable Banner for Customer Tag" checkbox.
Add tag in the Customer Tag field.
Then click on the Next button until the last steps.

Now, the shipping banner is shown to the customer who has Shopify tag, which you have added in the banner setting.

Note: Make sure customers in Shopify have the same tag you have set in the banner setting.