See the attached pictures for one example, when I typed $4.8 it changes to $5 when I click away from it, and when I click it again it changes back (temporarily). It sometimes does that and sometimes doesn't, I can't figure out why. Also when I use Sum to get the total it sometimes counts the number as it shows (rounded) and sometimes counts it as the way I typed it. How do change it to always show exact numbers?
I've never used Google Sheets, but as a general principle with spreadsheets the first thing I'd check is the formatting of that cell. If that cell is set to display to zero decimal places then that could explain it.
select your cell and then tap on the A with the lines at the top shown below. Then at the bottom select the Cell tab and scroll down until you see number format. Select number format and then you can assign the number of decimal places.