How to test data layer variables in Google Tag Manager?

In Google Tag Manager, I have some data layer variables set up. How can I test that the data is coming in through these variables as I expect? So, I want to verify that the data is getting collected in the dataLayer object (which can be done with Firebug, etc), but more importantly, I want to know that GTM is receiving the data, that the macros and rules are executing as expected, etc.

So, on the website, I have some code like this:

dataLayer = [];

dataLayer.push({
    'city': 'city name',
    'state': 'state name',
    'subtotalCost': 'subtotal $',
    'salesTax': 'sales tax $'
});

And then after this, I have the GTM code that loads gtm.js. This seems to be implemented correctly, however, I want to test that the values for the data layer variables are coming through as expected. Where can I check this at?

The console is your friend. What I would do is type dataLayer into the console after dataLayer.push, then click on the last object in the array and you'll see your values.

For instance, I put the dataLayer.push on an onclick event and ran dataLayer and was able to see this come through. Granted they are static values, but you get the idea.

UPDATE:

Google Tag Manager has updated their debugger, allowing you to see both Names or Values being passed into GTM.