To be honest, you probably shouldn't be asking for feedback on $1-$10 transactions, but for relatively high amounts like $100 - $1000, I think you deserve it as long as you're not begging. But until now, I haven't had any experience with this, so whatever I say is just an assumption.
You just giving a way for @OP to earn positive feedback by completing a trade that worth at least for $100, it really depends on case by case. Trading small amount money is worth to leave positive feedback too, especially when you think the account will scam since he doesn't have any reputation or get negative feedback.
I dont believe someone should been give a positive feedback just because of a single successful transaction. Its not the best use of the trust system in my opinion.
You don't need to have few successful trade in order to trust someone, a big money in single trade is worth for positive feedback.
However there are a lot inappropriate positive feedback used in this forum, I still think it's way more better to leave positive feedback for small amount trade rather than the user is scam buster, high rank, good guy, respected user etc.