Rewards Points Math (superman 3 problem)

So remember Superman 3 when Richard Pryor took all the pennies and eventually came up with millions?

I was placing a test order in the store today and it came to $9.44. I tried applying 80 rewards points toward it (I didn't need that many). It took 47 points and processed the order, but 47 points is only $9.40 and the order processed 4¢ short.

I'm thinking if our points equal 20¢ that we could lose up to 19¢ per order if the math works out not in our favor.

So thinking out some solutions, I came up with the following:
*Option 1:  Change our reward points to equal 1 penny.
*Option 2:  Find the line in the code and make it +1 as far as how many are needed.

Does anyone know where that line is in the code for Option 2?

Does anyone have any other suggestions?

Thanks!

Best wishes,
Andrea