In the P510063  Job Master Revisions  there is the field Posting Edit. It will prevent all posting to the Job if it is flagged with an "N".  This will prevent all accounts with this job from having anything posted to the accounts.  

 96CCVC                 Posting Edit - Business Unit           ( PECC       ) 
                                                                               
Controls whether you can post transactions to the general ledger for the job   
(business unit). Valid codes are:                                              
                                                                               
   Blank      Yes, you can post transactions.                                     
   K             Yes, you can post transactions. However, the original budget is     
                   locked and change orders are required for changes to the budget.    
   N             No, you cannot post transactions. Use this code for a job that is   
                   not started or is closed. The job closing program automatically     
                   assigns this code to all closed jobs.                               
   P             No, you cannot post transactions, and the job can be purged.