There are Vendor Bill-IItem Receipt Amount Tolerance Fields available in the vendor, item, and subsidiary records. But there is no matching action in the 3-way Match Vendor Bill Approval Workflow that comes from the NetSuite Approvals Workflow bundle.
Currently, the Amount Tolerance can be set only between Vendor Bill and Purchase Order. This has been reported in Enhancement 375395.
But it is possible to customize the workflow by taking a copy of the same. Add the actions using this standard field to match the amounts in Item Receipt and Vendor bill.