How to ROUNDUP and ROUNDDOWN with IF-function

I'm trying to make a number round up or round down depending on if it's higher or lower than 05..

If the number in A1 is for example 73, I want cell B1 to round UP to 75.

If the number in A1 is 78 I want B1 to round DOWN to 75.

So if I type a number between 50-54 it rounds up, and if I type a number between 56-59 it rounds down, and so on.

I have tried different functions for rounding up and down, but the only result I get is either a regular round up, or a regular round down. I can't figure out how to make it work both ways depending on what number I type.

I think I have to use =IF in some way, but can't figure out how.

This is my latest try.. and I'm lost! IF=A1<85;(ROUND.UP(A1;5(IF(A1>85;(ROUND.DOWN(A1;5)))))))

and I want it to round up and down not only between 80-89.. so even if my formula had been working it would only work for 80-89, and that's not what I'm trying to do.

Any suggestions?

Best regards, J