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	$90.25	7.266%	$96.8076	$96.81	$96.80	$96.80
Purchase #2	$9.89	4.396%	$10.3248	$10.32	$10.30	$10.30
Purchase #3	$53.43	8.188%	$57.8048	$57.80	$57.80	$57.80
Purchase #4	$97.91	13.488%	$111.1161	$111.12	$111.10	$111.10
Purchase #5	$165.78	13.745%	$188.5665	$188.57	$188.55	$188.60
Purchase #6	$146.61	4.619%	$153.3819	$153.38	$153.40	$153.40
Purchase #7	$244.44	4.753%	$256.0582	$256.06	$256.05	$256.10
7 purchase totals =	$808.31		$874.0599	$874.06	$874.00	$874.10