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	$62.92	13.410%	$71.3576	$71.36	$71.35	$71.40
Purchase #2	$61.78	3.302%	$63.82	$63.82	$63.80	$63.80
Purchase #3	$210.49	9.335%	$230.1392	$230.14	$230.15	$230.10
Purchase #4	$207.54	3.667%	$215.1505	$215.15	$215.15	$215.20
Purchase #5	$224.42	10.213%	$247.34	$247.34	$247.35	$247.30
Purchase #6	$97.34	13.747%	$110.7213	$110.72	$110.70	$110.70
Purchase #7	$77.77	7.867%	$83.8882	$83.89	$83.90	$83.90
7 purchase totals =	$942.26		$1,022.4168	$1,022.42	$1,022.40	$1,022.40