Generally speaking, the fine folks at retail outlets will treat you as nicely as anyone else regardless of the "gender appropriateness" of your purchase.

I've no illusions that when I go out en femme that I'm not read. I don't even try to pass anymore. On the contrary, even if I'm as masculinely as I ever am, I'm not shy about asking to try on whatever item I want to buy. Only once, in the last twenty-five years or so have I been denied, and that by a small second hand shop clerk where the owner had previously allowed it.

None of the major stores has ever made a big deal out of it. I stopped by Sears one afternoon on the way home from work, dressed in the uniform supplied by my employer, without a doubt very masculine. I was there on my way to the tool section, but stopped by the women's department to browse. I didn't have it in mind when I went in, but I saw a dress that really captured my attention. I took it to the check out counter and asked, "Is there some place I can try this on?" and was directed to the ladies fitting rooms.

So, if you're not going to even try on, then no one will care, even if they do think it strange. Truth is, they probably will forget any thoughts they have about you when the next customer shows up.