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	$173.83	6.545%	$185.2072	$185.21	$185.20	$185.20
Purchase #2	$19.85	12.745%	$22.3799	$22.38	$22.40	$22.40
Purchase #3	$140.93	7.696%	$151.776	$151.78	$151.80	$151.80
Purchase #4	$212.81	5.629%	$224.7891	$224.79	$224.80	$224.80
Purchase #5	$238.80	11.347%	$265.8966	$265.90	$265.90	$265.90
Purchase #6	$32.90	5.141%	$34.5914	$34.59	$34.60	$34.60
Purchase #7	$74.65	10.401%	$82.4143	$82.41	$82.40	$82.40
7 purchase totals =	$893.77		$967.0545	$967.06	$967.10	$967.10