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	$149.66	3.520%	$154.928	$154.93	$154.95	$154.90
Purchase #2	$49.50	8.144%	$53.5313	$53.53	$53.55	$53.50
Purchase #3	$205.44	9.265%	$224.474	$224.47	$224.45	$224.50
Purchase #4	$22.34	10.204%	$24.6196	$24.62	$24.60	$24.60
Purchase #5	$100.38	8.602%	$109.0147	$109.01	$109.00	$109.00
Purchase #6	$55.33	8.148%	$59.8383	$59.84	$59.85	$59.80
Purchase #7	$97.62	3.182%	$100.7263	$100.73	$100.75	$100.70
7 purchase totals =	$680.27		$727.1322	$727.13	$727.15	$727.00