This script demonstrates some problem with implicit conversion:

declare @v varchar(30)

,@f float

-- here you think it is all right and it is

set @f = 1.12

set @v = @f

select @v

-- here you think it is all right, but you get the wrong result

set @f = 123456.12

set @v = @f

select @v

-- worst and worst

set @f = 12345677.12

set @v = @f

select @v

-- correct solution

set @f = 12345677.12

set @v = CAST(@f AS DECIMAL(16,2))

select @v