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	$103.73	13.699%	$117.94	$117.94	$117.95	$117.90
Purchase #2	$72.66	6.631%	$77.4781	$77.48	$77.50	$77.50
Purchase #3	$29.29	12.592%	$32.9782	$32.98	$33.00	$33.00
Purchase #4	$241.66	9.612%	$264.8884	$264.89	$264.90	$264.90
Purchase #5	$32.76	3.225%	$33.8165	$33.82	$33.80	$33.80
Purchase #6	$154.60	9.291%	$168.9639	$168.96	$168.95	$169.00
Purchase #7	$240.73	6.327%	$255.961	$255.96	$255.95	$256.00
7 purchase totals =	$875.43		$952.0261	$952.03	$952.05	$952.10