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	$228.38	3.370%	$236.0764	$236.08	$236.10	$236.10
Purchase #2	$33.33	11.772%	$37.2536	$37.25	$37.25	$37.30
Purchase #3	$230.46	3.550%	$238.6413	$238.64	$238.65	$238.60
Purchase #4	$44.69	6.492%	$47.5913	$47.59	$47.60	$47.60
Purchase #5	$222.89	5.251%	$234.594	$234.59	$234.60	$234.60
Purchase #6	$58.61	4.358%	$61.1642	$61.16	$61.15	$61.20
Purchase #7	$138.37	10.450%	$152.8297	$152.83	$152.85	$152.80
7 purchase totals =	$956.73		$1,008.1505	$1,008.14	$1,008.20	$1,008.20