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	$130.78	5.257%	$137.6551	$137.66	$137.65	$137.70
Purchase #2	$63.52	3.521%	$65.7565	$65.76	$65.75	$65.80
Purchase #3	$152.47	11.593%	$170.1458	$170.15	$170.15	$170.10
Purchase #4	$59.89	5.141%	$62.9689	$62.97	$62.95	$63.00
Purchase #5	$151.32	3.834%	$157.1216	$157.12	$157.10	$157.10
Purchase #6	$218.39	6.695%	$233.0112	$233.01	$233.00	$233.00
Purchase #7	$179.64	10.727%	$198.91	$198.91	$198.90	$198.90
7 purchase totals =	$956.01		$1,025.5691	$1,025.58	$1,025.50	$1,025.60