Assign a value to numbers in a specific range

I created the following formula for rounding certificate of deposit terms (in days) to months. 

     round ((({CERTIFICATE_INFORMATION.TERM} / 365) * 12),0)

This works great for rounding the number to the nearest full month, but I need to take numbers in multiple ranges and assign a specific value.

Examples:  CD terms between: 

>0 months and <=2.5 months  (as calculated above) is assigned a value of 1

>2.5 months and <=5.5 months (as calculated above) is assigned a value of 3

>5.5 months and <=8.5 months "...................................................................." 6

>8.5 months and <=11.5 months ".................................................................." 9

"......................................................................................................................." 12

"......................................................................................................................." 18

and so forth up to 60 months

Thanks