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	$66.63	5.555%	$70.3313	$70.33	$70.35	$70.30
Purchase #2	$117.84	4.805%	$123.5022	$123.50	$123.50	$123.50
Purchase #3	$190.66	12.611%	$214.7041	$214.70	$214.70	$214.70
Purchase #4	$81.25	8.399%	$88.0742	$88.07	$88.05	$88.10
Purchase #5	$222.47	7.279%	$238.6636	$238.66	$238.65	$238.70
Purchase #6	$104.60	6.390%	$111.2839	$111.28	$111.30	$111.30
Purchase #7	$169.39	11.262%	$188.4667	$188.47	$188.45	$188.50
7 purchase totals =	$952.84		$1,035.0260	$1,035.01	$1,035.00	$1,035.10