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	$58.40	7.269%	$62.6451	$62.65	$62.65	$62.60
Purchase #2	$97.97	4.207%	$102.0916	$102.09	$102.10	$102.10
Purchase #3	$67.92	5.291%	$71.5136	$71.51	$71.50	$71.50
Purchase #4	$153.51	12.572%	$172.8093	$172.81	$172.80	$172.80
Purchase #5	$71.56	8.728%	$77.8058	$77.81	$77.80	$77.80
Purchase #6	$38.62	5.562%	$40.768	$40.77	$40.75	$40.80
Purchase #7	$173.84	12.797%	$196.0863	$196.09	$196.10	$196.10
7 purchase totals =	$661.82		$723.7197	$723.73	$723.70	$723.70