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	$73.31	13.146%	$82.9473	$82.95	$82.95	$82.90
Purchase #2	$75.49	9.227%	$82.4555	$82.46	$82.45	$82.50
Purchase #3	$24.78	3.260%	$25.5878	$25.59	$25.60	$25.60
Purchase #4	$83.58	11.752%	$93.4023	$93.40	$93.40	$93.40
Purchase #5	$84.83	5.459%	$89.4609	$89.46	$89.45	$89.50
Purchase #6	$68.95	8.248%	$74.637	$74.64	$74.65	$74.60
Purchase #7	$54.52	8.484%	$59.1455	$59.15	$59.15	$59.10
7 purchase totals =	$465.46		$507.6363	$507.65	$507.65	$507.60