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	$151.47	7.501%	$162.8318	$162.83	$162.85	$162.80
Purchase #2	$20.50	12.469%	$23.0561	$23.06	$23.05	$23.10
Purchase #3	$127.93	13.272%	$144.9089	$144.91	$144.90	$144.90
Purchase #4	$210.72	5.522%	$222.356	$222.36	$222.35	$222.40
Purchase #5	$245.36	3.376%	$253.6434	$253.64	$253.65	$253.60
Purchase #6	$126.60	12.575%	$142.52	$142.52	$142.50	$142.50
Purchase #7	$128.71	4.497%	$134.4981	$134.50	$134.50	$134.50
7 purchase totals =	$1,011.29		$1,083.8143	$1,083.82	$1,083.80	$1,083.80