That's what I do. I use the tap water conditioner for chlorine n stress coat just to make the fish happy. I do 1ml of each per 10 gallons so for 15 gallons that'd be 1.5ml of each.
But if your LFS stocks seachem prime get that instead of the api tap water conditioner. From what I'm reading its the best one to use. I myself don't use it because I have a big bottle of the api tap water conditioner, but when I run out I'll be switching over to it.
Not saying api doesn't work, if that's all your LFS has (guessing Petco, that's where I get my api stuff) just get that, works just as good.
Also as far as dosing goes, its not written in stone, but it works well for me and my fancy goldies along with a couple clown loaches and bristlenose plecos.