New rats/advice on socializing

I just bought new rats today, 2 females. I have had rats before but that was a looonng time ago. I bought them from a local pet store. There were alot of these young rats in one 10 gallon tank. I picked the 2 that were at least a little bit curious about me. I got them home and into there new cage and let them settle for about 2 hours. Then I went back to give them abit of attention. I expected them to be a little nervous but I have been trying all day and they still jump and squeek everytime I try to touch them. I don't remember my other rat being that scared of me from the start but as I said that was a long time ago. I even tried giving them a bit of apple. They wouldn't even sniff it while I was holding it. So could I get some suggestions? Should I leave them alone and give them more time to get used to the place? Or should I just keep trying. (by the way I do own a dog. she is very well behaved and only showed a little intrest in them for the first few minutes I was home with them.)  I left her scent on my hands because I would like them to get used to her too. Is this a mistake? Any info you could send my way would be very welcome!