Not an expert and not sure this will answer your query, however, just stating it
Please have a look at this site from money control. It has a field called contribution. When I add the contribution, I get the total of -276.54. This is exactly -0.73% as of Jan 21.
How exactly the contribution is calculated, I tried to search the net to find out but could not. Hope some experts will give a reply.
There is another post similar to this and this too remain inconclusive…