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	$173.74	13.338%	$196.9134	$196.91	$196.90	$196.90
Purchase #2	$50.27	4.173%	$52.3678	$52.37	$52.35	$52.40
Purchase #3	$238.72	6.802%	$254.9577	$254.96	$254.95	$255.00
Purchase #4	$39.70	3.473%	$41.0788	$41.08	$41.10	$41.10
Purchase #5	$198.91	4.860%	$208.577	$208.58	$208.60	$208.60
Purchase #6	$138.77	4.508%	$145.0258	$145.03	$145.05	$145.00
Purchase #7	$190.55	8.307%	$206.379	$206.38	$206.40	$206.40
7 purchase totals =	$1,030.66		$1,105.2995	$1,105.31	$1,105.35	$1,105.40