Well, I don't know where you live, but I have a lot of experience in Hamburg, Stuttgart, and Munich - not exactly known as cheap cities -, and spending 5 EUR on any one-way travel in the extended inner city is nearly impossible.
Maybe your experience is outdated. Specifically if you just cross a "circle" for Munich the one-way ticket is 5.40
Note that what they call "Inner District/Munich" is 4 circles and if you go again to the same circle you have to count it again. Like you go 2-1-2 it is 3 circles = 8.40 EUR.
I'm sorry, but that is wrong, and I hope you haven't overspend for long. There is a significant difference between rings and zones. There are just 4 zones (the coloured ones on this plan). For single-trip tickets, you only count the number of zones, not the number of rings. Anything in the white zone (which is all of the built-up area of Munich) is just one zone, and is (currently) EUR 2.70 per trip. The most you can pay is EUR 10.80, which is for "4+" zones, and allows you to travel, say, from Tutzing to the airport (nominally 7 zones). And you can get a group day ticket for the green and white zones for EUR 12.20, which gets you out to Lake Starnberg, then to the Garching campus of TUM, and back to Goetheplatz for Theatre...
The smaller rings are only used to calculate the price for subscriptions, not for single-trip and day tickets.