For sale events where per $10 USD spent on the store = one sale trading card, is that amount based on subtotal or the total (tax included)?

i really need to know. steam support is dodging my question. the horizontal progress bar on the cart checkout screen showed that i would receive 2 cards but i only got 1. before this purchase, i already got 1 card, this purchase session should have given me 2 sale trading cards based on the horizontal progress bar.

i used excel to make this:
subtotal tax total
0.99 0.06 1.05
9.05 0.56 9.61
6.99* 0.44 7.43
11.98 0.75 12.73

*14.98 - 7.99 (from refund)

Subtotal Sum = 29.01, but WITH tax total would be $30.82.

steam support conversations:

1. "..During the sale, you were intended to receive one sale trading card per $10 USD spent on the store.

This Sale has now ended. Steam Support cannot adjust the status of card drops or grant missing cards to your inventory..."

2. "...The best way to track your progress is to view the 'How do I earn card drops' link on the right of each badge's page. [bruh what? where even is this, is this the cart checkout screen with the progress bar?]

Sorry to hear you are having an issue unlocking sale items. Keep in mind that during the Sale, the Steam servers will sometimes be subjected to very high loads. This may cause item delivery to be delayed.

That being said, now that the Summer Sale has ended, no new trading cards will be awarded. Steam Support cannot adjust the status of drops, or grant missing cards.

Please submit all bugs to the Steam Trading Cards discussions.

I'm also forwarding your comments regarding the fees on to the appropriate department - we value feedback from the Steam community.

Additionally, if you wish to share an opinion, suggestion, or idea with the community as well, please visit the Suggestions/Ideas section of the Steam Discussion forums. 

Both forums are regularly read by Valve's development team..."