Maybe i'm reinventing hot water but no matter. It's fun for me :)))
These 2 functions round the number up or down on the decimal position we specify.

create function dbo.FloorEx(@num decimal(38, 33), @decimalPosition int)
returns decimal(38, 33)
as 
begin
if
  @decimalPosition < 0    set @decimalPosition = 0
return floor(@num*power(10, @decimalPosition))/power(10, @decimalPosition)
end
go
create function dbo.CeilingEx(@num decimal(38, 33), @decimalPosition int)
returns decimal(38, 33)
as 
begin
if
  @decimalPosition < 0    set @decimalPosition = 0
return ceiling(@num*power(10, @decimalPosition))/power(10, @decimalPosition)
end
go
 
declare
select @num decimal(38, 33), @decimalPosition int @num = 10.123456, @decimalPosition = 3
select
       dbo
       dbo
go @num, .FloorEx(@num , @decimalPosition), .CeilingEx(@num , @decimalPosition) 
drop function dbo.FloorEx
drop function dbo.CeilingEx