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	$12.49	12.623%	$14.0666	$14.07	$14.05	$14.10
Purchase #2	$50.70	13.860%	$57.727	$57.73	$57.75	$57.70
Purchase #3	$88.74	6.797%	$94.7717	$94.77	$94.75	$94.80
Purchase #4	$155.27	11.301%	$172.8171	$172.82	$172.80	$172.80
Purchase #5	$191.91	11.243%	$213.4864	$213.49	$213.50	$213.50
Purchase #6	$212.74	7.761%	$229.2508	$229.25	$229.25	$229.30
Purchase #7	$99.93	3.834%	$103.7613	$103.76	$103.75	$103.80
7 purchase totals =	$811.78		$885.8809	$885.89	$885.85	$886.00