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	$88.47	9.443%	$96.8242	$96.82	$96.80	$96.80
Purchase #2	$9.89	10.130%	$10.8919	$10.89	$10.90	$10.90
Purchase #3	$162.52	3.186%	$167.6979	$167.70	$167.70	$167.70
Purchase #4	$152.56	10.688%	$168.8656	$168.87	$168.85	$168.90
Purchase #5	$86.47	5.403%	$91.142	$91.14	$91.15	$91.10
Purchase #6	$11.87	8.558%	$12.8858	$12.89	$12.90	$12.90
Purchase #7	$70.69	7.433%	$75.9444	$75.94	$75.95	$75.90
7 purchase totals =	$582.47		$624.2518	$624.25	$624.25	$624.20