Hello.
I found this problem in the SUM() function.

Description:
When using the SUM() function to a range of negative and positive numbers in a column, with general formatting or Format -Number- standard, the result that should be 0, is a negative or positive number with exponential notation Like 2.8421709430404E-14.

The numbers used are natural numbers with two decimal digits.


Steps to reproduce
Create a spreadsheet and make a list of numbers like this
5.66
-5.66
10.81
20.3
2.54
4.56
9.87
165.25
-9.87
-165.25
-20.3
-2.54
-10.81
-4.56
in the end, the sum of all this numbers is 0

Use the SUM() function 
calc's result is -2.1316282072803E-14

copy transposed and the result in horizontal mode is the same.

If the formatting is used, the correct result ( 0 ) is displayed, but if the numbers are used in to a pivot table, the result is -0.00 but the real number is something like 0.000000000000028421709430404

When selecting the list of numbers and with shift down arrow, and setting the status bar to sum, you can see that as you advance in the selection, the result is a negative or positive number or 0 at some point, but when reaching the last element, the result in the status bar is also an infinitesimal value with exponential notation.

Tested with LO 4.4.5.2, 5.0.1.2, 5.0.2.2, 5.1.0.0 alpha1+ on windows 10

I'm submitting a test file.