If we a person bring in $11,000 for a cash deposit for a business, and $300 to exchange for smaller bills would we do the following:

Part I
Person conducting transaction for another: cash-in $11,300
Person on whose behalf transaction was conducted (the business): cash-in $11,300

and then in Part II, Line 25 Deposit: $11,000 and Currency exchange $300.

Yes. That's correct. You would not show the cash-out half of the currency exchange at all, because total cash-out is not more than $10,000.

So we would still show the money being exchanged on the business even though it does not affect the business account itself.

I'm being asked this and I say yes because it still affects the business because it's for the business and we need to list an account number for the business.

The reason you list an account number in your case is because there's a deposit being made that is also being reported. If the business hypothetically exchanged $11,000 in $100 bills for $11,000 in $20 bills, no account number would be listed in item 21 because no account is affected by the exchange. But you would list $11,000 as the cash amount for both items 21 and 22.