Joint Brokerage Accounts and Capital Gain/Loss Taxes with Nominee

I have a joint account with my sibling. I'm the primary account holder, so each year I file a 1096 with the correct 1099 form. We have never sold anything in the account, however we get dividends and interest, so I file the 1096 with the 1099-DIV and 1099-INT. We contribute to our account equally, so everything is 50/50 (at least that was our understanding with the contributions and tax part). So, when we do sell stocks, the capital gain/loss would also be split 50/50. 

 

I understand for the 1099-B, I would have to report each individual sale,  what I'm concerned about is when we sell stock with an odd number of shares. 

For example, lets say we bought and held 3 shares of stock A. We sell all 3 shares for a capital gain, how would we split it? I don't think writing 1.5 shares in the 1099-B would be correct, so any advice or tips would be greatly appreciated. 

A better way to ask, what do we do with the last odd share? 

 

Thanks to anyone in advance.