There are several strategies to deal with this. You need to consider the options and choose what is best for your situation.
1. Complete temperature control. This requires chillers, etc. to keep your chemicals at the required temperature for the entire processing time. Upside: ideal temperature control. Downside: expensive.
2. Ambient temperature processing. This requires you find a developer and dilution that does the job for you. Pyrocat or PMK may be good choices. Rodinal, as mentioned, is probably not. Upside: no added expense. Downsides: 1. You need to know your ambient temperature at the time of processing and adjust development times for variations accordingly. There are charts/tables for this, so it's not really that difficult, just one more thing to do. You may also have to adjust developer dilution and do tests to find your best developing times for higher temperatures in order to keep developing times from becoming too short. You may also have to experiment with some developers till you find one that works well. That said, once dialed in, this should be a good and economical solution. As Ian mentions, most modern films can be processed at 80°F with no concerns with many developers.
3. Temperature control with a water bath. This is not as precise as using a chiller with a thermostat, but works pretty well. You would have to keep some water in the refrigerator to mix chemicals and your water bath with. The idea is to have a large tub of tempered water that the chemicals can be immersed in in order to keep them from warming too quickly. The larger the volume of water in your bath, the slower it will warm. When processing, keep the tank and the not-yet-used chemicals immersed in the water bath except for agitation. Starting at 68° with an 80° ambient temperature will likely result in the temperature rising a few degrees by the end of processing. However, if you are consistent, this will not be an issue.
If you use tanks for roll films, the water-bath method works really well. Just pick up a tub large enough for all your chemical containers and tanks and a couple of gallon jugs to keep in the fridge (I bet you have drinking water there already, which would work just fine for your application).
If you tray develop sheet film, on the other hand, a water bath is a bit harder to manage. I usually have my developing trays inside the next larger size trays with water baths, but this is a relatively smaller volume of water and the temperature rise during processing might be larger if there is a significant difference between processing and ambient temperatures. Still, if you are consistent, there will be no problems. However, if the ambient temperature is a lot different in winter than in summer, or fluctuates a lot, this will be harder to control. Simplest in this case would be one of the first two methods.
Best,
Doremus