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	$208.82	4.810%	$218.8642	$218.86	$218.85	$218.90
Purchase #2	$23.39	10.612%	$25.8721	$25.87	$25.85	$25.90
Purchase #3	$70.89	3.201%	$73.1592	$73.16	$73.15	$73.20
Purchase #4	$240.89	5.279%	$253.6066	$253.61	$253.60	$253.60
Purchase #5	$133.31	6.340%	$141.7619	$141.76	$141.75	$141.80
Purchase #6	$205.54	11.247%	$228.6571	$228.66	$228.65	$228.70
Purchase #7	$198.50	12.803%	$223.914	$223.91	$223.90	$223.90
7 purchase totals =	$1,081.34		$1,165.8351	$1,165.83	$1,165.75	$1,166.00