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	$55.76	11.267%	$62.0425	$62.04	$62.05	$62.00
Purchase #2	$54.88	13.767%	$62.4353	$62.44	$62.45	$62.40
Purchase #3	$187.82	11.200%	$208.8558	$208.86	$208.85	$208.90
Purchase #4	$233.33	9.583%	$255.69	$255.69	$255.70	$255.70
Purchase #5	$70.37	9.107%	$76.7786	$76.78	$76.80	$76.80
Purchase #6	$136.89	6.365%	$145.603	$145.60	$145.60	$145.60
Purchase #7	$129.63	8.443%	$140.5747	$140.57	$140.55	$140.60
7 purchase totals =	$868.68		$951.9799	$951.98	$952.00	$952.00