Breeding unknown petstore rats is considered a real no-no!
You have unknown genetics, you could have some horrible health problems down the line...they could all die young with cancer, be extremely myco prone etc, etc. You may have bred high-white carriers and some of your litter could contract MC and die horrible painful deaths. You could have a pair of sweet parents and end up with highly aggressive babies. Your babies could all turn out to be all black berks since that is a dominant colour gene, and they are notoriously difficult to rehome.
The real breeders work thanklessly hard to improve the rat lines they have. They know the family backgrounds/traits of all of their rats. They will stay in contact with all their baby's adopters and if a problem crops up in a line, they will stop breeding that line. You deciding to put 2 petstore rats together is just taking all their work back to square one.
IF you decide to go ahead, you have to be prepared to keep all the babies you cannot rehome, be prepared to separate the males before 5 weeks of age so they can't impregnate the girls. You have to have a lot of money set aside for possible complications with the birth, or vet care later on. You'll need big cages just in case your girl drops a 13-16 eeper litter. I just went thru an oops litter of 13 this summer and it was exhausting. Adopters bailed on my babies, so I had to re-adopt quite a few and I still have the mom and 4 of her offspring. Be prepared for these babies to eat and eat and eat, and its up to you to make sure they get the appropriate foods for a good healthy start in life. You will need to handle the babies daily from just about Day 1 of their lives...its a lot of work in the end.
This is not an endeavour you should step into lightly. There are too many perfectly fine homeless rats out there for you to be creating more. If you want to breed properly, start reading up on genetics and get yourself a mentor amongst the breeders.