Whole bunch of examples where FLOAT (DOUBLE PRECISION) fails is in 1st topic.

Regarding second one:

DECLARE

@enumerator DECIMAL(38, 12)

,@denominator DECIMAL(38, 12)

SELECT

@enumerator = 50

,@denominator = 111.111

SELECT @enumerator/@denominator,

dbo.fn_BRound2(@enumerator/@denominator, 100)

,Round(@enumerator/@denominator,2)

Server: Msg 8115, Level 16, State 6, Procedure fn_Bround2, Line 7

Arithmetic overflow error converting float to data type numeric.

Try harder.