C172 Pilot reported complete electrical failure and landed at the nearest towered airport instead of returning to their departure airport.

Narrative

On DATE around XA30pm ET was doing touch-and-goes at ZZZ in a C172 from a flight school in ZZZ1 (where rented it from/I initially departed from). On last touch/go; I requested departure to south practice area to climb and get ATIS to go back to ZZZ1 (origin of flight). Upon my departure; shortly after ZZZ Tower gave me clearance to VFR and frequency change with south departure around 2000 ft. altitude; the com1 volume went out. I attempted to troubleshoot; switching to com2 radios; checking breakers; trying multiple frequencies; same issue. Com1 radio begins to fade display. Attempted to call ZZZ Tower on com2 but every transmit resulted in com2 going blank as well. Both coms are now out. Attempted to switch transponder to communications failure code. Transponder showed 7600 for a few seconds but then showed some kind of error message (off top of my head something about push a button to reset). I was attempting to troubleshoot in air about 2-4 miles SE of ZZZ. All radios/electronics/electrical system now fails (total electrical failure in air). I attempted to turn around and head back to ZZZ rather than ZZZ1 airspace. At this time; also noticed fuel gauges were falling to zero; and given the electrical failure; I had zero confidence in fuel level and actually thought I was leaking fuel and this was now an even bigger emergency situation. I felt out of the circumstances it was wise/concern for immediate life safety to land nearest/soonest runway so I immediately returned to ZZZ; but was too fast to land on first runway in sight; so I attempted to circle/tear drop around to the last runway I departed from; thinking I was going to lose my engine at any time. I think trying to lower the flaps before landing finally drained what was left of the battery. I believe I landed on Runway XX and the landing was normal/smooth; I taxi off the runway and waited for the green signal from the Tower. Taxi to their FBO; immediately notified the flight school (where I rented the plane from) of the situation and they told me to record the time; leave the keys and aircraft rental binder in the airplane. They sent someone out to pick me up and take me back to ZZZ1. I emailed/called/filled out a summary to the flight school yesterday but never heard back from them. After tie down; I was told by a representative from ZZZ Tower that an investigation from ZZZ airport staff showed the aircraft transponder was reporting altitude approximately 7000 ft. seconds before I landed (impossible) just before the total electrical failure. I believe this is an additional safety issue that need to be investigated and other pilots/ATC needs to be aware of. The transponder was giving potentially false speed/altitude information during this entire event; which could be a major safety issue; especially when it is in loss communication failure code mode. I wanted to communicate these issues out of caution.