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	$108.84	13.777%	$123.8349	$123.83	$123.85	$123.80
Purchase #2	$179.93	8.513%	$195.2474	$195.25	$195.25	$195.20
Purchase #3	$78.75	6.179%	$83.616	$83.62	$83.60	$83.60
Purchase #4	$135.85	10.533%	$150.1591	$150.16	$150.15	$150.20
Purchase #5	$93.69	10.807%	$103.8151	$103.82	$103.80	$103.80
Purchase #6	$97.60	5.718%	$103.1808	$103.18	$103.20	$103.20
Purchase #7	$239.32	8.392%	$259.4037	$259.40	$259.40	$259.40
7 purchase totals =	$933.98		$1,019.2570	$1,019.26	$1,019.25	$1,019.20