La única forma que se me ocurre para lograr esto es con una subconsulta correlacionada:
WITH CTE AS
( SELECT TranID,
TranLine,
ItemID,
OrderID,
Dollars,
Quantity,
SUM(dollars) OVER (PARTITION BY TranID, ItemID, OrderID ORDER BY TranLine) AS CumDollar,
SUM(Quantity) OVER (PARTITION BY TranID, ItemID, OrderID ORDER BY TranLine) AS CumQuantity
FROM T
)
SELECT TranID,
TranLine,
ItemID,
OrderID,
Dollars,
Quantity,
CumDollar,
CumQuantity,
( SELECT LISTAGG(Tranline, ';') WITHIN GROUP(ORDER BY CumQuantity)
FROM CTE T2
WHERE T1.CumQuantity >= T2.CumQuantity
AND T1.ItemID = T2.ItemID
AND T1.OrderID = T2.OrderID
AND T1.TranID = T2.TranID
GROUP BY tranid, itemid, orderid
) AS ListAgg
FROM CTE T1;
Me doy cuenta de que esto no da el resultado exacto que estabas pidiendo, pero espero que sea suficiente para superar el problema del LISTAGG acumulativo y ponerte en camino.
Configuré un SQL Fiddle para demostrar la solución.