Final answer:
Vouching sales journal entries to copies of sales orders, shipping documents, and sales invoices is an effective procedure to test the existence objective for sales.
Step-by-step explanation:
An effective procedure to test the existence objective for sales is to vouch sales journal entries to copies of sales orders, shipping documents, and sales invoices.
This process involves comparing the information recorded in the sales journal with the supporting documents to verify the occurrence of the sales transactions. By examining sales orders, shipping documents, and sales invoices, auditors can confirm that the recorded sales actually took place.
Therefore, the statement is True.