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	$162.39	8.151%	$175.6264	$175.63	$175.65	$175.60
Purchase #2	$23.60	4.661%	$24.7	$24.70	$24.70	$24.70
Purchase #3	$142.29	10.106%	$156.6698	$156.67	$156.65	$156.70
Purchase #4	$190.77	5.246%	$200.7778	$200.78	$200.80	$200.80
Purchase #5	$92.88	3.510%	$96.1401	$96.14	$96.15	$96.10
Purchase #6	$117.69	12.139%	$131.9764	$131.98	$132.00	$132.00
Purchase #7	$233.86	9.753%	$256.6684	$256.67	$256.65	$256.70
7 purchase totals =	$963.48		$1,042.5589	$1,042.57	$1,042.60	$1,042.60