I do not see an option for rounding in a magic ETL but you can use the round() function in a MySQL dataflow.  An example of how to use the function is below.  You can copy and paste this into a transform in a MySQL ETL to see how it works.  You would replace the 25.751 value with the column name that you want to round.

select 25.751 as my_value
, round(25.751) as whole_number
, round(25.751,1) as 1_decimal_place
, round(25.751,2) as 2_decimal_place

@user10714 I found your post today while searching how to do the same thing myself.  

I found a solution!  You can use a set column type tile and change the decimal to a whole number.  That rounds to the nearest whole number.

I also thought about converting the decimal to text and then breaking it apart with string operations, then combining back together, and then converting back to decimal.

Hope this helps you, or the next person to search this topic!