Losing weight, need some jean advice

I wasn't sure if this could have been in Fitness, but I figured you guys would have a more suited answer for me.

So I've been loosing weight as of recently, and I'm going to be buying some new clothes with Holiday gift cards. Here's my concern: I don't know what I should do about the size of jeans to purchase. Should I invest in half sizes? Should I go down a size? I ask this question because I'm on a roll with what I'm doing and I don't want to end up with jeans too big or too small within a matter of a few months.