Auditing Specific Expense Types

Is there the ability to 100% audit a specific expense type, no matter the currency used, which doesn't involve policy violations as we don't want to confuse the end user

The only rule I've seen you can set up per particular expense type includes a currency column which is mandatory so we cannot audit the expense type fully as we use a 10s of different currencies regularly.

The alternative as I say is to set the policy for that type to anything over £0.01 but then this means the user will be flagged for violating this every time.