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	$95.74	11.400%	$106.6544	$106.65	$106.65	$106.70
Purchase #2	$148.45	3.522%	$153.6784	$153.68	$153.70	$153.70
Purchase #3	$150.59	12.621%	$169.596	$169.60	$169.60	$169.60
Purchase #4	$145.33	11.573%	$162.149	$162.15	$162.15	$162.10
Purchase #5	$85.69	5.582%	$90.4732	$90.47	$90.45	$90.50
Purchase #6	$127.55	6.202%	$135.4607	$135.46	$135.45	$135.50
Purchase #7	$230.92	4.509%	$241.3322	$241.33	$241.35	$241.30
7 purchase totals =	$984.27		$1,059.3439	$1,059.34	$1,059.35	$1,059.40