Proper way to exclude SQL files from backup

It appears that my file level backups are actually backing up some of the SQL files on my SQL Servers. The reason I say this is, when I do a file level backup of the system, it puts an entry in the SQL transaction log that then screws up my SQL backups. What is the proper way to exclude all SQL files from file level backups? Here is my current MSSQL exclude directive that obviously isn't working:

<< "C:\" >>
+skip: *.ldf *.LDF *.mdf *.MDF *.ndf *.NDF
+aes: *.*
+compressasm: .

<<"C:\i386">>
+skip:.?**

<< "D:\" >>
+skip: *.ldf *.LDF *.mdf *.MDF *.ndf *.NDF
+aes: *.*
+compressasm: .

<< / >>
+skip: *.ldf *.LDF *.mdf *.MDF *.ndf *.NDF
+aes: *.*
+compressasm: .

Thank you!