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	$196.34	9.517%	$215.0257	$215.03	$215.05	$215.00
Purchase #2	$21.62	12.143%	$24.2453	$24.25	$24.25	$24.20
Purchase #3	$17.60	6.363%	$18.7199	$18.72	$18.70	$18.70
Purchase #4	$58.48	5.696%	$61.811	$61.81	$61.80	$61.80
Purchase #5	$192.81	3.673%	$199.8919	$199.89	$199.90	$199.90
Purchase #6	$148.50	7.282%	$159.3138	$159.31	$159.30	$159.30
Purchase #7	$57.89	13.856%	$65.9112	$65.91	$65.90	$65.90
7 purchase totals =	$693.24		$744.9188	$744.92	$744.90	$744.80