I think I've figured out what I was doing wrong, and as usual it is a face palm kind of problem. I was mistaking the format that the GPS was spitting out (4041.4335 as an example) as 40 degrees, 41 minutes, 43.35 seconds but it appears that this is actually 40 degrees, 41.4335 minutes. I am going to wait until I am driving around before I decide if this was truly the problem but in this format it does seem to put me within 20 yards or so of my house on google maps.