"Saving on the parrot's chocolate is futile"

Solution 1:

The term penny-wise refers to being "careful in dealing with small sums of money or small matters". It's commonly found in the phrase penny wise, pound foolish, meaning "Someone who is penny wise, pound foolish can be very careful or mean with small amounts of money, yet wasteful and extravagant with large sums."

You may also find the term bikeshedding of interest:

The word ... implies technical disputes over minor, marginal issues conducted while more serious ones are being overlooked. The implied image is of people arguing over what color to paint the bicycle shed while the house is not finished.

The term cheeseparing economy refers to "a useless economy." According to ngrams for cheeseparing economy it is occasionally but not frequently used. The phrase "strain at a gnat and swallow a camel", from Matthew 23:23, means "to fuss about trifles while ignoring more serious matters" (per reference.com) or "to criticize other people for minor offenses while ignoring major offenses" (per thefreedictionary.com). For related phrases, also see questions #41508 and #39726.

Solution 2:

One idiomatic way to refer to a measure that doesn't make much difference would be a drop in the bucket or a drop in the ocean.

drop in the bucket

(idiomatic) An effort or action having very little overall influence, especially as compared to a huge problem.

A $100 donation from an individual is generous, but it is a drop in the bucket compared to the $100,000 fundraising goal.