just a thought...but appears to work, but maybe I am not entirely clear on the issue

IF OBJECT_ID('Tempdb..#Redondeo') IS NOT NULL

DROP TABLE #Redondeo

CREATE TABLE #Redondeo (

Orden INT Identity(1, 1)

, Valores MONEY

)

INSERT INTO #Redondeo

SELECT 71374.24 UNION

SELECT 16455.92 UNION

SELECT 56454.20 UNION

SELECT 9495.18 UNION

SELECT 23894.20

SELECT Orden

, Valores

,round (Valores * 0.21,2) as rnd

FROM #Redondeo

SELECT Orden

, Valores

,round (Valores * 0.21,2) as rnd

into #testsum

FROM #Redondeo

SELECT SUM(rnd) AS sumbyrow

FROM #testsum

SELECT SUM(ROUND(Valores * 0.21, 2)) AS sumrnd

FROM #Redondeo