Persist/Commit question

Hi,

I have a basic question.
Is Persist command in Agent actions same as Commit(Apply database changes) and 'Dont Persist' same as Rollback of database changes?

Ex:I have an order in OTM and I sent an inbound XML to OTM with RC transaction code with the following change.
Modified the volume from 10 to 15 cuft on an order line in the XML.

So as soon as XML hits the OTM the database first gets updated with the above volume change and then Order modify agent gets invoked. If I put DONT persist after an IF condition in the order modify agent, does the volume change will be removed from database?Pls let me know if this is the way the database updates and persist command works in OTM