Math sale

So, I was like, waiting for someone outside a restaurant and it was soooooo hot, at least as hot as it's been this year, but I was in the shade, so it wasn't too bad, but still I was almost prespiring just standing there. Ick! Anyways, there was this store on the other side of the street that was having a grand opening sale. On the sign, it read:

For each

$50 take off $5
$100 take off $15
$150 take off $20

And I was like, OMGWTF!!!!?????