There are 3 versions of "On Target".
1. On Target Precision Calculator v2.10 (v2.14 now in testing phase)
2. On Target TDS (Target Data System) v3.78 just released
3. On Target Scoring used for ARA & PSL matches used in conjunction with a large flatbed scanner for the regulation size targets.
Do you have one of these versions of "On Target" or are you considering which one you want?
The "On Target TDS" will show a composite or virtual group of all the shots you fire at seperate bulls with targets printed from the program. It will provide the pertinent statistics, including what you asked about, and I think this version is the one you'd be most interested in.
Here's a link to it.