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	$210.77	5.433%	$222.2211	$222.22	$222.20	$222.20
Purchase #2	$95.69	13.350%	$108.4646	$108.46	$108.45	$108.50
Purchase #3	$87.72	7.751%	$94.5192	$94.52	$94.50	$94.50
Purchase #4	$222.72	5.786%	$235.6066	$235.61	$235.60	$235.60
Purchase #5	$209.46	3.452%	$216.6906	$216.69	$216.70	$216.70
Purchase #6	$214.73	9.510%	$235.1508	$235.15	$235.15	$235.20
Purchase #7	$35.43	5.209%	$37.2755	$37.28	$37.30	$37.30
7 purchase totals =	$1,076.52		$1,149.9284	$1,149.93	$1,149.90	$1,150.00