"Hello"
Sale tax is a percentage the country takes from every sale made on the local market. When a citizen sells goods, this share of the price goes to the country budget instead of the seller.
Raising it sends more money to the country budget on each sale, but sellers keep less, which can push them to raise prices or sell less.
Lowering it lets sellers keep more of each sale, which can encourage trade and lower prices, while the country budget collects less.
This is a neutral explanation to help you decide — it doesn't favor either side.