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	$144.52	5.153%	$151.9671	$151.97	$151.95	$152.00
Purchase #2	$122.45	3.854%	$127.1692	$127.17	$127.15	$127.20
Purchase #3	$132.26	6.121%	$140.3556	$140.36	$140.35	$140.40
Purchase #4	$13.53	10.440%	$14.9425	$14.94	$14.95	$14.90
Purchase #5	$206.95	7.687%	$222.8582	$222.86	$222.85	$222.90
Purchase #6	$163.40	5.437%	$172.2841	$172.28	$172.30	$172.30
Purchase #7	$219.49	8.655%	$238.4869	$238.49	$238.50	$238.50
7 purchase totals =	$1,002.60		$1,068.0636	$1,068.07	$1,068.05	$1,068.20