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	$87.74	10.471%	$96.9273	$96.93	$96.95	$96.90
Purchase #2	$122.89	11.801%	$137.3922	$137.39	$137.40	$137.40
Purchase #3	$52.62	4.478%	$54.9763	$54.98	$55.00	$55.00
Purchase #4	$122.88	6.273%	$130.5883	$130.59	$130.60	$130.60
Purchase #5	$188.63	3.341%	$194.9321	$194.93	$194.95	$194.90
Purchase #6	$54.96	10.873%	$60.9358	$60.94	$60.95	$60.90
Purchase #7	$127.32	12.139%	$142.7754	$142.78	$142.80	$142.80
7 purchase totals =	$757.04		$818.5274	$818.54	$818.65	$818.50