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	$108.65	5.146%	$114.2411	$114.24	$114.25	$114.20
Purchase #2	$141.52	6.475%	$150.6834	$150.68	$150.70	$150.70
Purchase #3	$210.66	13.396%	$238.88	$238.88	$238.90	$238.90
Purchase #4	$68.66	7.700%	$73.9468	$73.95	$73.95	$73.90
Purchase #5	$73.62	5.375%	$77.5771	$77.58	$77.60	$77.60
Purchase #6	$95.70	7.794%	$103.1589	$103.16	$103.15	$103.20
Purchase #7	$238.69	7.155%	$255.7683	$255.77	$255.75	$255.80
7 purchase totals =	$937.50		$1,014.2556	$1,014.26	$1,014.30	$1,014.30