Look ate this:
WITH cte AS (
SELECT
LXA.AuctionID
, ISNULL(MAX(LXA.BidPrice), 0) AS MaxBidPrice
FROM LiveXAuctionBid LXA
GROUP BY LXA.AuctionID
)
SELECT
LXA.AuctionID
,LAD.OpeningPrice
,AP.Description
,UR.Name
,UR.BigLeapID
,CONVERT(VARCHAR,LXA.Date)Date
,CASE WHEN LXA.IsAutoBid=1 then cte.MaxBidPrice +LAD.BidIncrement else LXA.BidPrice End topay
FROM LiveXAuctionBid LXA
INNER JOIN cte ON LXA.AuctionID = cte.AuctionID
INNER JOIN LiveAuctionBid LA ON LA.LiveAuctionBidID = LXA.LiveAuctionBidID
INNER JOIN UserRegistration UR ON UR.UserRegistrationID = LA.UserID
INNER JOIN LiveAuctionDetails LAD ON LAD.LiveAuctionDetailID = LXA.AuctionID
INNER JOIN AuctionProduct AP ON AP.AuctionProductID = LAD.ProductID
WHERE LAD.LiveAuctionDetailID = @LiveAuctionDetailID
GROUP BY LXA.AuctionID,LAD.OpeningPrice,AP.Description,UR.Name,UR.ID,Date