After some more testing i found out that for every decimal between .005 and .995 with a step .01 (=.005, .015, .025,. .035, etc....) you get a different result in the basic numbers that a rounded wrong.

FOR lnDecimal = 0.005 TO 0.115 STEP 0.01
  lnExpected = ROUND(lnDecimal,2)
  FOR lnValueBasic = 1 TO 200
    lnValue = lnValueBasic + lnDecimal
    lnValueLong = ROUND(lnValue,11)
    lnValueRound = ROUND(lnValueLong,2)
    lnDifferenceBasic_Round=lnValueRound-lnValueBasic && has to be lnExpected
    IF lnDifferenceBasic_Round <> lnExpected
      MESSAGEBOX('lnDecimal='+ALLTRIM(STR(lnDecimal,10,3))+', lnBasicValue='+ALLTRIM(STR(lnValueBasic,10,0)))
    ENDIF
  ENDFOR
ENDFOR

Also the number of decimals can make a difference in the result:

FOR lnDecimalRound = 11 TO 12
  FOR lnValueBasic = 1 TO 128
    lnValue = lnValueBasic + 0.325
    lnValueLong = ROUND(lnValue,lnDecimalRound)
    lnValueRound = ROUND(lnValueLong,2)
    lnDifferenceBasic_Round=lnValueRound-lnValueBasic && has to be 0.33
    IF lnDifferenceBasic_Round <> 0.33
      MESSAGEBOX('lnDecimalRound='+ALLTRIM(STR(lnDecimalRound,10,0))+', lnBasicValue='+ALLTRIM(STR(lnValueBasic,10,0)))
    ENDIF
  ENDFOR
ENDFOR

Please help! I'm losing it... I use this round() function a lot!!! And i mean thousands of times in my app's...

Willem-Jan van Ede
Vektis BV