Personally Aric I'd suggest 4 females, 1 male. Make sure the females are of the proper age and size...around 4 to 5 months but not over 9 months for first breeding. Put them in tandem, 2 females at a time with the male and then pull the first set out when you see signs they are preggie, pop in your second set. That way you can have litters at different stages and sizes to suit most of your size requirements. With having a breeding buddy system like this, if one of your females has too many in her litter you can foster them to your other female in that pairing and not lose any that way.

It takes awhile to get a breeder/feeder rat colony running right to completely support all your feeder needs but it's well worth it in my opinion. I personally don't like to leave my male in with females and their litters, or have more than one female in an enclosure with a litter but that's just my way of managing my own colony. It's worked extremely well for me but as in all aspects of husbandry, to keep his/her own as long as the animals are thriving.

Just make sure your breeder stock is very healthy and not closely related (pretty hard to manage in some pet stores but hey it's worth a mention). There's a ton of threads in the Feeder Forum about rat breeding that should be a lot of help for you.