USDT is extremely stable and is a stable coin class of crypto. Pretty much always $1 or like $1.01 so yes any bitmart sales go to USDT. I have a bunch in my Bitmart account and am waiting for the prices I like to buy more of some. Bitmart also has a bid and ask price so you don't have to buy at market if you don't want to. You can set an ask price to buy and a bid price to sell. just like Etrade or Ameritrade for stocks.
I just started a new crypto board to talk about cryptos, especially micro cryptos, where millionaires can be made, just by losing some zeros. Just search Micro Alt Crytos or Let's Lose Some Zeros or link in my profile. Come pay a visit. Brand new.