Lunchtime math

Here's a lunchtime math related story.
I was attempting to purchase a chicken sandwich at the cafeteria today, it was labeled as $5.75. This meal includes a 12oz fountain drink. Instead of the fountain drink, I chose a bottle of apple juice that costs $1.75.

My total at the cashier, $8.06. I asked why it was so high, since the sandwich comes with a drink, and the conversation went like this.
Him: There's a price difference of 75 cents
Me: OK
Him: Do you want to pay 75 cents more?
Me: Uh...
Him: OK, your total is $7.00

So there you have it, I paid 75 cents more for a discount of $1.06

(I did figure it out though:
$5.75 + $1.75 + tax = $8.06
$5.75 + tax = $6.25
$5.75 + $1.25 + tax = $7.00

So, I did pay 75 cents more, but he originally wanted to charge me for a fountain drink I didn't get)