Description:
drawing a chart from data in Calc, it's impossible to show the decimals of the percentage, even if the proper decimal format is selected

Steps to Reproduce:
1.create a Calc file with numeric data
2.click on Insert chart
3.Create Chart (e.g. pie chart)
4.Right-click on the chart -> Insert Data labels
5.Right-click on data labels -> Format data labels -> Data Labels -> put the check mark on "Show value as percentage"-> open "percentage format" -> deselect "source format"-> choose category "percent" & format 12,95% (or create another format with one or more digits after decimal dot or comma ).


Actual Results:
The percentage shown will anyway be approximated to the integer. (e.g. 19% instead of 18.68% or 18.7%)

Expected Results:
The percentage will be shown with decimal separator and one or more digits after it


Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 6.3.5.2
Build ID: 1:6.3.5-0ubuntu0.19.10.1
CPU threads: 2; OS: Linux 5.3; UI render: default; VCL: gtk3; 
Locale: it-IT (it_IT.UTF-8); UI-Language: en-GB
Calc: threadedVersion: 6.3.5.2
Build ID: 1:6.3.5-0ubuntu0.19.10.1
CPU threads: 2; OS: Linux 5.3; UI render: default; VCL: gtk3; 
Locale: it-IT (it_IT.UTF-8); UI-Language: en-GB
Calc: threaded

[Information automatically included from LibreOffice]
Locale: it
Module: ChartDocument
[Information guessed from browser]
OS: Linux (All)
OS is 64bit: yes