I got the padding wrong on the last version.  Here is a corrected version of
FORMAT (attached) and test cases.

(expect "     1.020" (format "~10,3F" 1.02))

(expect "     1.025" (format "~10,3F" 1.025))

(expect "     1.026" (format "~10,3F" 1.0256))

(expect "     1.002" (format "~10,3F" 1.002))

(expect "     1.002" (format "~10,3F" 1.0025))

(expect "     1.003" (format "~10,3F" 1.00256))

Additional test cases welcome.

Cheers,
-KenD