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	$69.63	3.187%	$71.8491	$71.85	$71.85	$71.80
Purchase #2	$108.85	13.560%	$123.6101	$123.61	$123.60	$123.60
Purchase #3	$10.36	5.335%	$10.9127	$10.91	$10.90	$10.90
Purchase #4	$139.73	10.657%	$154.621	$154.62	$154.60	$154.60
Purchase #5	$97.46	3.507%	$100.8779	$100.88	$100.90	$100.90
Purchase #6	$153.93	3.603%	$159.4761	$159.48	$159.50	$159.50
Purchase #7	$85.47	13.275%	$96.8161	$96.82	$96.80	$96.80
7 purchase totals =	$665.43		$718.1630	$718.17	$718.15	$718.10