Week of Month as a number

I am looking to determine what week a date occurs within a particular month.

I know there is a 53 number system, but I really need to have it show as 1-5 system.

For instance

12-15-2014 would be = 3

12-22-2014 would be = 4

01-01-2015 would be = 1

01-05-2015 would be = 2

03-31-2015 would be = 5

etc...

If DATEPART("ww", {SALES.SALEDATE}, crSunday) = 3 then

Unless I am looking at this incorrectly (could be I am a newbie) the above works great with the 53 number system, but using it I would have to utilize an else if for every one of the 53 weeks and would have to rewrite that every single year as the days/weeks change year to year.

So is there an easy way to determine week number for each individual month of the current year?

Then see if my {field.date} matches one of those 1-5 week numbers?

Thanks for the assistance.