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	$91.70	4.640%	$95.9549	$95.95	$95.95	$96.00
Purchase #2	$167.93	13.792%	$191.0909	$191.09	$191.10	$191.10
Purchase #3	$143.30	13.640%	$162.8461	$162.85	$162.85	$162.80
Purchase #4	$145.74	10.227%	$160.6448	$160.64	$160.65	$160.60
Purchase #5	$215.92	5.468%	$227.7265	$227.73	$227.75	$227.70
Purchase #6	$59.79	9.108%	$65.2357	$65.24	$65.25	$65.20
Purchase #7	$236.78	13.436%	$268.5938	$268.59	$268.60	$268.60
7 purchase totals =	$1,061.16		$1,172.0927	$1,172.09	$1,172.15	$1,172.00