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	$190.59	13.556%	$216.4264	$216.43	$216.45	$216.40
Purchase #2	$8.41	5.240%	$8.8507	$8.85	$8.85	$8.90
Purchase #3	$91.76	12.625%	$103.3447	$103.34	$103.35	$103.30
Purchase #4	$148.52	6.267%	$157.8277	$157.83	$157.85	$157.80
Purchase #5	$165.34	4.160%	$172.2181	$172.22	$172.20	$172.20
Purchase #6	$75.33	13.675%	$85.6314	$85.63	$85.65	$85.60
Purchase #7	$245.97	10.840%	$272.6331	$272.63	$272.65	$272.60
7 purchase totals =	$925.92		$1,016.9321	$1,016.93	$1,017.00	$1,016.80