A noble goal, but it apparently backfired on them spectacularly because of the same reason why retailers did that in the first place.
It's basically impossible that your customer was paying you in cash at that point anyways.
That's quite literaly against the "various rules to try to ensure neither the seller or buyer always benefited" that the previous commenter was talking about writing software to handle.
No country that has cash rounding rules would allow 2*1.03 to be charged $2.10.
https://en.m.wikipedia.org/wiki/Cash_rounding
(Unless you mean: the price of a single item is changed to $1.05, in which case sure; that's the business's perogative to raise prices but it's not taking advantage of the rounding system)
Worth mentioning that despite not having a one-cent denomination, products are still priced in cents - e.g. in Canada you still price something at $2.79 even though we have no pennies. It's only at the payment step, when cash is being used, that anything is rounded off.
I mean, retailers could certainly increase their shelf prices, but if they were going to do that they would do so anyway, and the $X.99 pricing pattern exists for a reason so there's not really anywhere to increase those prices by some small amount that wouldn't put people off anywa.