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	$171.65	12.444%	$193.0101	$193.01	$193.00	$193.00
Purchase #2	$94.87	9.364%	$103.7536	$103.75	$103.75	$103.80
Purchase #3	$87.47	4.627%	$91.5172	$91.52	$91.50	$91.50
Purchase #4	$178.55	11.606%	$199.2725	$199.27	$199.25	$199.30
Purchase #5	$57.74	13.596%	$65.5903	$65.59	$65.60	$65.60
Purchase #6	$172.77	7.412%	$185.5757	$185.58	$185.60	$185.60
Purchase #7	$244.76	9.378%	$267.7136	$267.71	$267.70	$267.70
7 purchase totals =	$1,007.81		$1,106.4330	$1,106.43	$1,106.40	$1,106.50