Finally back home from my exploration trip and done with selling the data
Results are about 99,5 mill credits and exploration rank pushed from Pathfinder 36% to Pioneer 51%
So as promised in my introduction post, here the system with the 5 black holes:
GREA EAESCS AA-A H9
Location in the galaxy: http://imgur.com/QAn10oD
System value: 802549 Cr
Totally worth the time needed for a full scan if one is in the area