Number systems: Rounding in different bases

Maths

Round 343 (base 10) to the nearest 10 (base 10)

If the units digit is 5 or higher round down. If it's lower than 5 round up

If the units digit is 5 or higher round up. If it's lower than 5 round down

If the units digit is higher than 5 round up. If it's lower than 5 round down. If its 5 stay the same.

What rule do we use when rounding to the nearest ten

Round 101(base 5) to the nearest 10(base 5)

If the units digit is 3 or higher round down. If it's lower than 3 round up

If the units digit is 3 or higher round up. If it's lower than 3 round down

If the units digit is higher than 3 round up. If it's lower than 3 round down. If its 3 stay the same.

What rule do we use when rounding to the nearest 10(base 5)

21(base 5) is bigger than 21(base10). True or false?