Well that would explain it. Is there any reason they can only do it in $500 increments? That's a weirdly arbitrary rule when money is in fact deliberately designed to be divisible.
> I.R.C. § 219(b)(5)(C)(ii) Rounding Rules — If any amount after adjustment under clause (i) is not a multiple of $500, such amount shall be rounded to the next lower multiple of $500.
https://irc.bloombergtax.com/public/uscode/doc/irc/section_2...
A married couple with both working at companies offering 401k gets to save $40k+ pre tax, but a married couple with one spouse working at a local small shop not offering 401k gets to save half as much.
Doesn't the owner want to save for retirement?
And admin costs are going down; I think something like $50 +$8/per/mo on Guideline. Not nothing obviously, but can be recouped pretty quickly if you're maxing out even just employee contribution.