How to change product’s price

Hi Team

I have 2 questions.

01. I want to change my price rule. Currently the rule is multiply x2 and I want to make it multiply x1.80
Which one should I use?
1.80 or 1,80 ?

02.I need to have a “beautifull” price. For example one of my products costs 46.15 and I want to be 47$
How can I do that?

Looking forward to your reply
Ioannis