Formula Help Needed

Hi all,

 

Looking for some help with a function, the issue i have is;

 

I have a formula which calculates the time difference between two entered times, this part works fine.

 

Then the next formula =FLOOR(P20,1/48) will round this down to the nearest 30 mins.

 

What i need to create is an argument that essentially says, if the time is less than 1 hour it is rounded to zero, but if it is more than one hour it rounds to the nearest 30 mins.

 

Can anyone help?

 

Thanks,

 

Richie