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	$182.89	11.310%	$203.5749	$203.57	$203.55	$203.60
Purchase #2	$7.56	13.158%	$8.5547	$8.55	$8.55	$8.60
Purchase #3	$115.63	6.822%	$123.5183	$123.52	$123.50	$123.50
Purchase #4	$73.79	4.580%	$77.1696	$77.17	$77.15	$77.20
Purchase #5	$244.95	4.192%	$255.2183	$255.22	$255.20	$255.20
Purchase #6	$37.47	10.128%	$41.265	$41.27	$41.25	$41.30
Purchase #7	$92.72	11.260%	$103.1603	$103.16	$103.15	$103.20
7 purchase totals =	$755.01		$812.4611	$812.46	$812.35	$812.60