If the hundredths place (the second digit after the decimal point) is 5-9, then the tenths place must be rounded up.

If the hundredths place (the second digit after the decimal point) is 5, 6, 7, 8, or 9, then the tenths place must be rounded up. Since the hundredths place is a 9, then you would round up 0.79 to 0.80.