How to stop printing sales invoice

Hi, 

I need to block printing sales invoice in code. For free text invoices I can use PrintOut parameter which I'm changing in CustPostInvoiceJob.custPostInvoiceUpdate method when necesarry, but it doesn't work for invoices related to sales table. 

I need to change it in place where I will have access to CustInvoiceJour record. Blocking logic is complicated so let's say I want to block printing invoice if invoiceId ends with "2". 

Please advise how can I achieve this.