ImportHTML spreadsheet function to update every 5 mins

Question

I have a Google Spreadsheet fetching stock exchange data using an ImportHTML function:

=ImportHtml("http://www.xxxx.xx.xx/xxxxxxxx/livefeedfull.aspx/?"& year(now()) & month(now()) & day(now()) & hour(now()) & MINUTE(),"table",0)  

that I then publish to a JSON which updates on every change. This function however updates every minute.

How do I set it to update at intervals of five minutes?

Answer 1

UNTESTED (because for example the Nairobi Stock Exchange is closed at present) but

& year(now()) & month(now()) & day(now()) & hour(now()) & MINUTE(),  

to

& A1,

with =int(minute(now())/5) in A1 may be worth trying.