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	$149.70	4.615%	$156.6087	$156.61	$156.60	$156.60
Purchase #2	$93.91	12.834%	$105.9624	$105.96	$105.95	$106.00
Purchase #3	$213.43	9.720%	$234.1754	$234.18	$234.20	$234.20
Purchase #4	$245.63	3.583%	$254.4309	$254.43	$254.45	$254.40
Purchase #5	$81.56	5.227%	$85.8231	$85.82	$85.80	$85.80
Purchase #6	$155.34	11.122%	$172.6169	$172.62	$172.60	$172.60
Purchase #7	$13.25	5.472%	$13.975	$13.98	$14.00	$14.00
7 purchase totals =	$952.82		$1,023.5924	$1,023.60	$1,023.60	$1,023.60