How to determine the cost basis for a Money Market fund?

I held a Municipal Money Market fund in my investment portfolio for many years, which was recently sold. The price of the product was $1.00, the quantity was 975.63, and the proceeds from the sale were $958.63.  I received a 1099-B for this sale. When I imported/downloaded the transaction into TurboTax Deluxe from the financial institution, TurboTax is prompting me to enter a costs basis; also, it defaults the Sales category field to "Box B - Short Term noncovered".  It is my understanding that money market funds are similar to bank accounts where the cost basis is not applicable.  How do I handle this situation in TurboTax?