round time to nearest 15mins e.g. 16:12 to 16:15

Hi

I am building a project tracker time thing in excel and need the value in a cell (which reads over from another cell) to round to the NEAREST 0.25 for

The multiples need to be 0.25, 0.5, 0.75 and a whole number


for example 15:43 needs to round to 15:45 as we only monitor in complete 15 minutes.

Thank you in advance