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	$53.62	11.367%	$59.715	$59.72	$59.70	$59.70
Purchase #2	$153.39	10.109%	$168.8962	$168.90	$168.90	$168.90
Purchase #3	$217.93	8.871%	$237.2626	$237.26	$237.25	$237.30
Purchase #4	$123.28	6.612%	$131.4313	$131.43	$131.45	$131.40
Purchase #5	$16.92	5.228%	$17.8046	$17.80	$17.80	$17.80
Purchase #6	$183.70	11.144%	$204.1715	$204.17	$204.15	$204.20
Purchase #7	$217.36	11.344%	$242.0173	$242.02	$242.00	$242.00
7 purchase totals =	$966.20		$1,061.2985	$1,061.30	$1,061.25	$1,061.30