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	$92.28	13.767%	$104.9842	$104.98	$105.00	$105.00
Purchase #2	$10.41	4.253%	$10.8527	$10.85	$10.85	$10.90
Purchase #3	$225.63	3.575%	$233.6963	$233.70	$233.70	$233.70
Purchase #4	$32.67	5.659%	$34.5188	$34.52	$34.50	$34.50
Purchase #5	$23.55	3.354%	$24.3399	$24.34	$24.35	$24.30
Purchase #6	$52.53	4.165%	$54.7179	$54.72	$54.70	$54.70
Purchase #7	$44.58	7.180%	$47.7808	$47.78	$47.80	$47.80
7 purchase totals =	$481.65		$510.8906	$510.89	$510.90	$510.90