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	$56.74	4.823%	$59.4766	$59.48	$59.50	$59.50
Purchase #2	$121.68	4.335%	$126.9548	$126.95	$126.95	$127.00
Purchase #3	$133.67	6.142%	$141.88	$141.88	$141.90	$141.90
Purchase #4	$208.89	11.838%	$233.6184	$233.62	$233.60	$233.60
Purchase #5	$150.78	10.388%	$166.443	$166.44	$166.45	$166.40
Purchase #6	$210.96	7.325%	$226.4128	$226.41	$226.40	$226.40
Purchase #7	$137.36	8.816%	$149.4697	$149.47	$149.45	$149.50
7 purchase totals =	$1,020.08		$1,104.2553	$1,104.25	$1,104.25	$1,104.30