I rent a booth in a antique store. What income do I declare - gross sales before sales commission or net sales after commission?

In this example what is the federal income that I report for tax purposes?  My gross sales for the month is $100, the store keeps $10 sales commission and gives me a check for $90.  Is it A) The store's income to declare is $10 and mine is $90, or B) My income to declare is $100 with a $10 expense for commission?  I assume A is the right answer but need to be sure.  Thanks!