This is some sort of employee stock option.  Per IRS instructions the 1099-B cost basis reported is the purchase/exercise price of the stock.  The taxpayer's cost basis is then adjusted by the amount of the gain on exercise that's already been included as compensation in their W-2.  So for calculating taxable gain, use the supplemental report (which includes the compensation piece of the basis.)  In your example, gain would be $2,940.99.

My guess is that there was a sales commission of $29.91 which is reducing the gross sales proceeds down to the net sales proceeds reported on the 1099-B.  This is correct too.