I have a number of sub totals and a grand total on my spreadsheet - each containing Sterling currency. If all are set to show 2 decimal places all works OK but if I hide the decimals in the sub totals and then add or subtract figures the grand total only responds to whole pounds i.e. the pence value only alters if the sub totals display pence. I am not using roundup or rounddown
Check if Options-LibreOffice Calc-Calculate-General Calculations-Precision as shown is checked.
Created attachment 141255 [details] Snapshot of Options
So, as you show on your screenshot, the "Precision as shown" is indeed selected. Thus, Calc uses numbers *as displayed in cells* for further calculations. If you show a subtotal as a whole number, and then use it in calculations of total, it's expected to behave as you describe. Unselect the option to resolve the issue. In general, I'd not use it. If you need some values to have limited precision, use ROUND. Closing NOTABUG.
Thanks very much :-)