1 US dollar is equal to (on May 29th, 2019) about 1,535 Myanmar kyats, according to google and the Myanmar's federal bank . Don't worry though, common bills range from 100 to 5,000 kyats, and most establishments in cities take US dollars. However, it is made painfully clear by every website I look at that only the crispest and most pristine dollars will be accepted; no smudges, no creases or folds. Before coming to Myanmar, be sure to iron your money. I've heard that only some places will take credit cards, so be prepared and bring lots of cash.
A couple of sites I saw said that haggling in street side shops and marketplaces is permissible, because base prices are high. But do this good naturedly, treat it as though it's not a competition. Don't do this in high-end establishments.