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	$97.33	13.678%	$110.6428	$110.64	$110.65	$110.60
Purchase #2	$59.30	13.383%	$67.2361	$67.24	$67.25	$67.20
Purchase #3	$244.72	7.506%	$263.0887	$263.09	$263.10	$263.10
Purchase #4	$32.97	12.526%	$37.0998	$37.10	$37.10	$37.10
Purchase #5	$61.76	6.549%	$65.8047	$65.80	$65.80	$65.80
Purchase #6	$136.88	10.363%	$151.0649	$151.06	$151.05	$151.10
Purchase #7	$21.91	11.651%	$24.4627	$24.46	$24.45	$24.50
7 purchase totals =	$654.87		$719.3997	$719.39	$719.40	$719.40