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	$182.92	5.832%	$193.5879	$193.59	$193.60	$193.60
Purchase #2	$248.79	6.356%	$264.6031	$264.60	$264.60	$264.60
Purchase #3	$115.34	7.346%	$123.8129	$123.81	$123.80	$123.80
Purchase #4	$158.72	13.261%	$179.7679	$179.77	$179.75	$179.80
Purchase #5	$25.48	4.168%	$26.542	$26.54	$26.55	$26.50
Purchase #6	$222.26	6.491%	$236.6869	$236.69	$236.70	$236.70
Purchase #7	$112.55	13.410%	$127.643	$127.64	$127.65	$127.60
7 purchase totals =	$1,066.06		$1,152.6437	$1,152.64	$1,152.65	$1,152.60