Plucking amounts out of PDFs

I have a pile of PDFs like this one (an image of one in this case):

That have been OCR'd via my Scansnap scanner.
The scanned text looks like this:
What I'd like to do is pluck out the HST amount ($2.70) and the final total ($20.75) and put those amounts in the file name.
My rules already can pull the date out and rename it correctly but how to get those two amounts out is a bit puzzling.
Suggestions? Thanks!

That have been OCR'd via my Scansnap scanner.
The scanned text looks like this:
Patty Bo land's 101 Clarence St. Ottawa, Ont.
Table #200
Trans #: 210809 Serv; Tiffers
10/16/2015 5:38 PM # Cust:1 Quan Descript Cost
1 Soft Drink $3.75 1 Bacon Delight Bu:ger $16.00 1 ->1/2 Fry 1/2 Salad $1.00
Net Total: $20.75 HST $2.70
TOTAL: $23.45 Amount Due: $23.45
Watch for New Daily Specials
What I'd like to do is pluck out the HST amount ($2.70) and the final total ($20.75) and put those amounts in the file name.
My rules already can pull the date out and rename it correctly but how to get those two amounts out is a bit puzzling.
Suggestions? Thanks!