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	$85.33	11.180%	$94.8699	$94.87	$94.85	$94.90
Purchase #2	$196.28	13.768%	$223.3038	$223.30	$223.30	$223.30
Purchase #3	$148.37	6.518%	$158.0408	$158.04	$158.05	$158.00
Purchase #4	$188.69	8.607%	$204.9305	$204.93	$204.95	$204.90
Purchase #5	$210.66	6.192%	$223.7041	$223.70	$223.70	$223.70
Purchase #6	$51.49	6.444%	$54.808	$54.81	$54.80	$54.80
Purchase #7	$113.36	12.437%	$127.4586	$127.46	$127.45	$127.50
7 purchase totals =	$994.18		$1,087.1157	$1,087.11	$1,087.10	$1,087.10