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	$162.54	6.204%	$172.624	$172.62	$172.60	$172.60
Purchase #2	$185.39	3.131%	$191.1946	$191.19	$191.20	$191.20
Purchase #3	$21.77	9.704%	$23.8826	$23.88	$23.90	$23.90
Purchase #4	$130.31	9.569%	$142.7794	$142.78	$142.80	$142.80
Purchase #5	$34.51	8.492%	$37.4406	$37.44	$37.45	$37.40
Purchase #6	$234.58	3.643%	$243.1257	$243.13	$243.15	$243.10
Purchase #7	$221.34	5.637%	$233.8169	$233.82	$233.80	$233.80
7 purchase totals =	$990.44		$1,044.8638	$1,044.86	$1,044.90	$1,044.80