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	$185.67	3.496%	$192.161	$192.16	$192.15	$192.20
Purchase #2	$162.49	13.104%	$183.7827	$183.78	$183.80	$183.80
Purchase #3	$70.62	7.460%	$75.8883	$75.89	$75.90	$75.90
Purchase #4	$61.78	5.834%	$65.3842	$65.38	$65.40	$65.40
Purchase #5	$112.57	12.382%	$126.5084	$126.51	$126.50	$126.50
Purchase #6	$226.83	12.701%	$255.6397	$255.64	$255.65	$255.60
Purchase #7	$211.89	10.375%	$233.8736	$233.87	$233.85	$233.90
7 purchase totals =	$1,031.85		$1,133.2379	$1,133.23	$1,133.25	$1,133.30