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	$162.56	11.696%	$181.573	$181.57	$181.55	$181.60
Purchase #2	$24.81	3.747%	$25.7396	$25.74	$25.75	$25.70
Purchase #3	$103.87	8.382%	$112.5764	$112.58	$112.60	$112.60
Purchase #4	$241.69	9.330%	$264.2397	$264.24	$264.25	$264.20
Purchase #5	$49.64	8.531%	$53.8748	$53.87	$53.85	$53.90
Purchase #6	$226.86	12.102%	$254.3146	$254.31	$254.30	$254.30
Purchase #7	$175.57	7.576%	$188.8712	$188.87	$188.85	$188.90
7 purchase totals =	$985.00		$1,081.1893	$1,081.18	$1,081.15	$1,081.20