John,
Yes this is the proper way!
You don't need to add any SubTotal.
SubTo stores the value, in order to do some calculations further (like update the credit limit of customer etc.). This is not a mandatory field.
From a concept level - in field From, press F1 and read the SAP F1 Help.
From value is the base value for a condition type.
On the base value, a discount of 5% can be calculated etc.
Added: MJ is correct about step 50 and 60, both these should have From = 25 (instead of 10). As your base price is at step 25.
Thanks MJ 
Message was edited by: TW Typewriter - added in blue color
