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	$72.33	5.121%	$76.034	$76.03	$76.05	$76.00
Purchase #2	$92.59	8.180%	$100.1639	$100.16	$100.15	$100.20
Purchase #3	$141.59	12.831%	$159.7574	$159.76	$159.75	$159.80
Purchase #4	$89.84	10.314%	$99.1061	$99.11	$99.10	$99.10
Purchase #5	$208.47	10.189%	$229.711	$229.71	$229.70	$229.70
Purchase #6	$175.31	4.472%	$183.1499	$183.15	$183.15	$183.10
Purchase #7	$206.71	9.748%	$226.8601	$226.86	$226.85	$226.90
7 purchase totals =	$986.84		$1,074.7824	$1,074.78	$1,074.75	$1,074.80