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	$168.31	4.369%	$175.6635	$175.66	$175.65	$175.70
Purchase #2	$80.95	13.144%	$91.5901	$91.59	$91.60	$91.60
Purchase #3	$174.77	12.338%	$196.3331	$196.33	$196.35	$196.30
Purchase #4	$26.32	8.677%	$28.6038	$28.60	$28.60	$28.60
Purchase #5	$175.81	13.588%	$199.6991	$199.70	$199.70	$199.70
Purchase #6	$145.47	3.421%	$150.4465	$150.45	$150.45	$150.40
Purchase #7	$90.65	5.846%	$95.9494	$95.95	$95.95	$95.90
7 purchase totals =	$862.28		$938.2855	$938.28	$938.30	$938.20