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	$224.89	8.301%	$243.5581	$243.56	$243.55	$243.60
Purchase #2	$125.79	5.133%	$132.2468	$132.25	$132.25	$132.20
Purchase #3	$87.48	12.688%	$98.5795	$98.58	$98.60	$98.60
Purchase #4	$198.26	8.390%	$214.894	$214.89	$214.90	$214.90
Purchase #5	$110.64	11.766%	$123.6579	$123.66	$123.65	$123.70
Purchase #6	$18.69	10.341%	$20.6227	$20.62	$20.60	$20.60
Purchase #7	$243.88	3.259%	$251.828	$251.83	$251.85	$251.80
7 purchase totals =	$1,009.63		$1,085.3870	$1,085.39	$1,085.40	$1,085.40