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	$242.33	9.106%	$264.3966	$264.40	$264.40	$264.40
Purchase #2	$6.89	9.420%	$7.539	$7.54	$7.55	$7.50
Purchase #3	$21.78	10.522%	$24.0717	$24.07	$24.05	$24.10
Purchase #4	$162.50	11.525%	$181.2281	$181.23	$181.25	$181.20
Purchase #5	$185.47	13.858%	$211.1724	$211.17	$211.15	$211.20
Purchase #6	$132.49	9.774%	$145.4396	$145.44	$145.45	$145.40
Purchase #7	$230.83	13.852%	$262.8046	$262.80	$262.80	$262.80
7 purchase totals =	$982.29		$1,096.6520	$1,096.65	$1,096.65	$1,096.60