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	$104.85	4.781%	$109.8629	$109.86	$109.85	$109.90
Purchase #2	$59.73	8.295%	$64.6846	$64.68	$64.70	$64.70
Purchase #3	$192.93	10.807%	$213.7799	$213.78	$213.80	$213.80
Purchase #4	$142.32	11.358%	$158.4847	$158.48	$158.50	$158.50
Purchase #5	$163.45	6.142%	$173.4891	$173.49	$173.50	$173.50
Purchase #6	$111.35	10.784%	$123.358	$123.36	$123.35	$123.40
Purchase #7	$197.65	13.246%	$223.8307	$223.83	$223.85	$223.80
7 purchase totals =	$972.28		$1,067.4899	$1,067.48	$1,067.55	$1,067.60