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	$125.69	6.442%	$133.7869	$133.79	$133.80	$133.80
Purchase #2	$35.45	4.186%	$36.9339	$36.93	$36.95	$36.90
Purchase #3	$82.72	5.349%	$87.1447	$87.14	$87.15	$87.10
Purchase #4	$170.89	12.580%	$192.388	$192.39	$192.40	$192.40
Purchase #5	$39.75	5.697%	$42.0146	$42.01	$42.00	$42.00
Purchase #6	$85.83	11.135%	$95.3872	$95.39	$95.40	$95.40
Purchase #7	$159.45	8.297%	$172.6796	$172.68	$172.70	$172.70
7 purchase totals =	$699.78		$760.3349	$760.33	$760.40	$760.30