how to perform oracle ceil with decimal points

In round function we can use (4,512,1) but the same is not true for ceil and floor. I want to ceil and my floor the value 4,512 as 4,5 and 4,6 but the decimal point 1 is not always constant. it may vary. For Floor with decimal points the trunc function can be used. Is there a way to perform ceil with decimal points ?

Adapting how the round function is defined (for positive numbers):

ROUND(n, integer) = FLOOR(n * POWER(10, integer) + 0.5) * POWER(10, -integer)

... for a general case of a variable ceiling you might want something like:

ceil(n * power(10, integer)) * power(10, -integer)

So you could define your own functions:

create or replace function my_ceil(p_number number, p_decimals pls_integer)
return number as
begin
  return ceil(p_number * power(10, p_decimals)) * power(10, -p_decimals);
end;
/

create or replace function my_floor(p_number number, p_decimals pls_integer)
return number as
begin
  return floor(p_number * power(10, p_decimals)) * power(10, -p_decimals);
end;
/

Then with some sample data:

with t (n) as (
  select 4.512 from dual union all
  select 5.12345 from dual union all
  select 6 from dual union all
  select 0 from dual union all
  select -1.23 from dual
)
select n, 0 as d, my_ceil(n, 0) as my_ceil, my_floor(n, 0) as my_floor from t
union all
select n, 1 as d, my_ceil(n, 1), my_floor(n, 1) from t
union all
select n, 2 as d, my_ceil(n, 2), my_floor(n, 2) from t
union all
select n, 3 as d, my_ceil(n, 3), my_floor(n, 3) from t
union all
select n, 4 as d, my_ceil(n, 4), my_floor(n, 4) from t
order by n, d

you get:

db<>fiddle

You might need to look at negative values to check they behave as you expect/want, and adjust the functions to mimic round if necessary. You also said the decimal might be zero, 1 or more; if that could be negative then it will need more work...