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	$164.25	5.635%	$173.5055	$173.51	$173.50	$173.50
Purchase #2	$82.28	10.318%	$90.7697	$90.77	$90.75	$90.80
Purchase #3	$86.50	10.170%	$95.2971	$95.30	$95.30	$95.30
Purchase #4	$232.70	9.404%	$254.5831	$254.58	$254.60	$254.60
Purchase #5	$88.41	7.423%	$94.9727	$94.97	$94.95	$95.00
Purchase #6	$238.89	7.524%	$256.8641	$256.86	$256.85	$256.90
Purchase #7	$161.66	5.433%	$170.443	$170.44	$170.45	$170.40
7 purchase totals =	$1,054.69		$1,136.4352	$1,136.43	$1,136.40	$1,136.50