This is a well known and well designed psychology trick it tricks the brain into believing something is cheaper or makes it seem the price to be more attractive.
The whole 0.99 thing is to stop cashiers stealing from tills. They can easily pocket a £10 note without being spotted but with £9.99 they have to count the change.
1. wrong placement of dollar sign
2. it's a psychological trick designed to make shoppers feel like it's 10 dollars but it's 11 dollars-1 cent, scamming the shopper out of 99 cents