Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.25	5.680%	$194.7154	$194.72	$194.70	$194.70
Purchase #2	$138.83	12.823%	$156.6322	$156.63	$156.65	$156.60
Purchase #3	$92.58	5.555%	$97.7228	$97.72	$97.70	$97.70
Purchase #4	$243.28	10.521%	$268.8755	$268.88	$268.90	$268.90
Purchase #5	$43.58	10.812%	$48.2919	$48.29	$48.30	$48.30
Purchase #6	$120.51	5.620%	$127.2827	$127.28	$127.30	$127.30
Purchase #7	$190.66	13.288%	$215.9949	$215.99	$216.00	$216.00
7 purchase totals =	$1,013.69		$1,109.5154	$1,109.51	$1,109.55	$1,109.50