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	$57.46	3.819%	$59.6544	$59.65	$59.65	$59.70
Purchase #2	$86.31	9.677%	$94.6622	$94.66	$94.65	$94.70
Purchase #3	$195.70	4.693%	$204.8842	$204.88	$204.90	$204.90
Purchase #4	$216.84	7.335%	$232.7452	$232.75	$232.75	$232.70
Purchase #5	$55.75	6.488%	$59.3671	$59.37	$59.35	$59.40
Purchase #6	$76.96	10.670%	$85.1716	$85.17	$85.15	$85.20
Purchase #7	$20.38	9.640%	$22.3446	$22.34	$22.35	$22.30
7 purchase totals =	$709.40		$758.8293	$758.82	$758.80	$758.90