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	$82.49	3.515%	$85.3895	$85.39	$85.40	$85.40
Purchase #2	$116.85	8.122%	$126.3406	$126.34	$126.35	$126.30
Purchase #3	$127.37	9.146%	$139.0193	$139.02	$139.00	$139.00
Purchase #4	$88.82	6.653%	$94.7292	$94.73	$94.75	$94.70
Purchase #5	$71.83	9.796%	$78.8665	$78.87	$78.85	$78.90
Purchase #6	$46.45	10.831%	$51.481	$51.48	$51.50	$51.50
Purchase #7	$122.72	4.110%	$127.7638	$127.76	$127.75	$127.80
7 purchase totals =	$656.53		$703.5899	$703.59	$703.60	$703.60