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	$77.83	12.484%	$87.5463	$87.55	$87.55	$87.50
Purchase #2	$99.32	4.190%	$103.4815	$103.48	$103.50	$103.50
Purchase #3	$105.39	5.784%	$111.4858	$111.49	$111.50	$111.50
Purchase #4	$129.55	13.685%	$147.2789	$147.28	$147.30	$147.30
Purchase #5	$205.77	5.199%	$216.468	$216.47	$216.45	$216.50
Purchase #6	$11.68	10.729%	$12.9331	$12.93	$12.95	$12.90
Purchase #7	$33.68	11.833%	$37.6654	$37.67	$37.65	$37.70
7 purchase totals =	$663.22		$716.8590	$716.87	$716.90	$716.90