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	$149.82	7.314%	$160.7778	$160.78	$160.80	$160.80
Purchase #2	$18.41	11.821%	$20.5862	$20.59	$20.60	$20.60
Purchase #3	$50.70	5.737%	$53.6087	$53.61	$53.60	$53.60
Purchase #4	$33.33	11.176%	$37.055	$37.06	$37.05	$37.10
Purchase #5	$83.97	12.651%	$94.593	$94.59	$94.60	$94.60
Purchase #6	$182.38	9.282%	$199.3085	$199.31	$199.30	$199.30
Purchase #7	$146.63	6.453%	$156.092	$156.09	$156.10	$156.10
7 purchase totals =	$665.24		$722.0212	$722.03	$722.05	$722.10