Stealing from a store is 1% chance of success per point above store skill, capping at 100%. EG if the store has 15, then 16 gives you 1% chance to succeed.

Stealing from a target is 1% chance of success per point above target skill, minus 1%, capping at 99%. EG if the target has 15, then 17 gives you 1% chance to succeed.

Slot difficulty is the minimum required skill for any chance of success on that item.

per this conversation

Suggestions
Bugs