Converting time into 15 minute billing units

[Tom_M_1969]

I'm fighting with the problem of converting time (h:mm) into 15 minute billing units, while always rounding down to the lowest number of full units. 
 
I'm using Microsoft® Excel® for Microsoft 365 MSO (Version 2110 Build 16.0.14527.20234) 64-bit on a Windows 10 PC.
 
For example, if the time I'm dealing with is 14 minutes, that would round down to zero units. 16 minutes would round down to 1 unit. 29 minutes would also round down to 1 unit. In the attached sample document:
 
0:15 = 1 unit
1:14 = 4 units
0:31 = 2 units
0:45 = 3 units
 
Any suggestions would be appreciated. Thanks.

[#2 · Accepted solution]

@Tom_M_1969 

In C5:

=QUOTIENT(B5,TIME(0,15,0))

Fill down.

[#3]

Thank you!