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Wow, you've got several massive water changes in your near future. 5ppm of ammonia is extremely toxic and deadly to your fish. The way they are reduced is by doing large and frequent water changes with fresh, temperature matched, dechlorinated water.
I would immediately go do a 75% water change, let the water circulate for 15 minutes and do another 75% change. After that, test your levels and see where they are. The goal during a fish-in cycle should be to keep ammonia and nitrIte at or below .25 at all times until the tank is cycled.
Having a quality dechlorinator like Seachem Prime can be a big help as well because it will temporarily neutralize the toxins for 24-36 hours.
Here's a great guide to help you (and especially your fish) through it.
http://www.aquariumadvice.com/forums/f15/i-just-learned-about-cycling-but-i-already-have-fish-what-now-116287.html
I don't mean to sound negative, but this is an emergency situation and your fish are suffering...I hope you go do the water changes as soon as you finish reading this post.