Paragraphs 2 and 3 are in fact one sentence:
Der Räuber hatte - wie berichtet - den allein anwesenden Tankstellenpächter mit einem Revolver bedroht und zur Herausgabe der Tageseinnahmen gezwungen.
The robber had - as reported - threatened the gas station tenant, who was alone, with a revolver and forced him to hand over the day's takings.
A shorter version (only relevant parts) is this:
Der Räuber hatte den Tankstellenpächter zur Herausgabe der Tageseinnahmen gezwungen.
The robber had forced the gas station tenant to hand over the day's takings.
The English construction is different from the German. In German you could say the same idea also this way:
Der Räuber hatte den Tankstellenpächter gezwungen, die Tageseinnahmen herauszugeben.
This alternative German version fits better to the English sentence, because it uses a grammatical construction, that is more similar to the one used in the English sentence. The word "herauszugeben" is an "erweiterter Infinitiv" of the verb "herausgeben" (to hand over) and "to hand over" is also an infinite form of a verb.
But "Die Herausgabe" from the original sentence is a noun. (An uppercase first letter at a word that is not the first word of a sentence always indicates a noun!) There is no exact English translation for the German noun die Herausgabe. The closest try would be "the handovering" or "the handoveration" with a meaning similar to "the transfer", but such an English word doesn't exist. So, if you try to create an English translation that uses a grammar similar to the German sentence, you would get something like this:
The robber had forced the gas station tenant to the handovering of the day's takings.
The robber had forced the gas station tenant to the transfer of the day's takings.
And I think now it should be clear what is it that the day's takings are possessing. They possess the handover-process.
You asked who possesses the day's takings, but it's the other way around. In "Der Hut des Mannes" ("The hat of the man"), it's not the hat that owns the man. It's the other way around. The genitive attribute is the owner (the one who owns something) and the core noun of the nominal group is the thing that is owned by the genitive attribute.
btw: Your textbook is old. Mark is no valid currency since 2002.