Eight Coins for the Surveyor's Lunch

Two farmhands, Anya and Boris, sit down to lunch just as a traveling surveyor asks to join them. Anya has brought $5$ flatbreads and Boris $3$; they pool all $8$, and the three of them eat exactly equal amounts. Afterward the grateful surveyor leaves $8$ copper coins to pay for his share. Anya suggests splitting the coins $5{:}3$ to match what each packed. What division is actually fair — proportional to how much bread each farmhand gave the surveyor?