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	$112.88	9.433%	$123.528	$123.53	$123.55	$123.50
Purchase #2	$115.79	7.501%	$124.4754	$124.48	$124.50	$124.50
Purchase #3	$24.82	13.727%	$28.227	$28.23	$28.25	$28.20
Purchase #4	$238.95	8.548%	$259.3754	$259.38	$259.40	$259.40
Purchase #5	$193.26	6.339%	$205.5108	$205.51	$205.50	$205.50
Purchase #6	$106.72	10.340%	$117.7548	$117.75	$117.75	$117.80
Purchase #7	$133.42	8.510%	$144.774	$144.77	$144.75	$144.80
7 purchase totals =	$925.84		$1,003.6454	$1,003.65	$1,003.70	$1,003.70