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	$176.82	10.846%	$195.9979	$196.00	$196.00	$196.00
Purchase #2	$125.35	10.785%	$138.869	$138.87	$138.85	$138.90
Purchase #3	$123.86	5.639%	$130.8445	$130.84	$130.85	$130.80
Purchase #4	$80.72	10.253%	$88.9962	$89.00	$89.00	$89.00
Purchase #5	$242.58	5.399%	$255.6769	$255.68	$255.70	$255.70
Purchase #6	$147.96	8.625%	$160.7216	$160.72	$160.70	$160.70
Purchase #7	$166.75	11.147%	$185.3376	$185.34	$185.35	$185.30
7 purchase totals =	$1,064.04		$1,156.4437	$1,156.45	$1,156.45	$1,156.40