Commerce 2: How to Implement State, County and City Sales Tax?

Unfortunately the Commerce 2 documentation is still completely blank for this section ( https://docs.drupalcommerce.org/commerce2/user-guide/taxes/us-sales-tax ). There are a number of questions I have regarding the implementation of this portion of an e-commerce store.

Let's take the case of New York State in the United States. New York State's Department of Taxation and Finance says:

"New York's retail sales tax is a destination tax. The point of delivery or the point at which possession is transferred by the seller to the purchaser determines the rate of tax to be collected."

That means that you need to program into the Commerce 2.0 store:

1. The state sales tax: 4%
2. Each county's sales tax: most of the counties charge 4%, but it does vary. Each county will have to be specified individually in case their county government decides to raise or lower their rate.
3. The cities that also have a city sales tax.

That means that I need to maintain a massive list of all zip codes for every county as well as each city that charges sales tax.  Which isn't easy, because zip codes do not go in order by county.  For example (these are real codes and counties in NYS):

12070 - Montgomery
12071 - Schoharie
12072 - Montgomery
12073 - Schoharie
12074 - Saratoga
12075 - Columbia
12076 - Schoharie
12077 - Albany
12078 - Fulton
 

Here are some of the many questions that I (and I assume others) would have regarding coding all of this information:

1. When you define a Tax Type, what exactly is a "Territory"?
    
2. How do you specify the one state rate, all of the county rates, as well as all of the additional city rates?
    
3. How many different zip codes are allowed for each entry? How many characters are allowed in each field?
    
4. Can a zip code be specified more than once in the overall list? ie, the first appearance for county, and then a second appearance for city?
    
5. In the checkout, are each of the different tax types shown on separate lines - ie, state, county and city - and then are totaled in yet another line?
    

Has anyone implemented a complex state such as New York State in their store? How did you do it, and how large/extensive was your Tax Type section in the configuration?

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The above was originally written under the assumption (perhaps erroneously) that everything would and could be coded under a single tax entry. So I instead tried defining entries for my home state (PA), along with another entry for my county and one for my city as well.

In a separate private browsing window I put items in the cart, created a new account, entered my personal credit card and address (which would have satisfied all three state, county AND city requirements based on zip code). NO SALES TAX was displayed when reviewing during checkout. So why aren't taxes working?