Scalar function not behaving consistently in query

In the following scalar function,

a fractional value between 0.1 and 0.4 is set to 0.5

a fractional value of 0.6 and above is rounded up to the next integer

ALTER FUNCTION [dbo].[BHERound]
(
    @val float
)
RETURNS float
AS
BEGIN
    -- Declare the return variable here
    declare @frac float      --fractional part of the value
    declare @newfrac float

    Set @frac = @val - round(@val,0,1) 

    set @newfrac = 0

    If  @frac >= 0.1 and @frac <=0.4
        set @newfrac = 0.5
    else if @frac >= 0.6
        set @newfrac = 1
    else if @frac > 0.4 and @frac < 0.6
        set @newfrac = 0.5

    return     round(@val,0,1) + @newfrac

END

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this works fine in SMSS e.g.

select dbo.BHERound(1.6) , gives the answer 2, as expected

however the following query

select *,dbo.BHERound(RawBHE) as BHE from tblTESTRawBHE where PosRef='FCILLC002220'

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returns

i.e 1.5 which is wrong, RawBHE is a FLOAT data type.