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	$194.30	7.475%	$208.8239	$208.82	$208.80	$208.80
Purchase #2	$32.42	7.610%	$34.8872	$34.89	$34.90	$34.90
Purchase #3	$107.59	5.260%	$113.2492	$113.25	$113.25	$113.20
Purchase #4	$58.96	4.687%	$61.7235	$61.72	$61.70	$61.70
Purchase #5	$207.52	10.434%	$229.1726	$229.17	$229.15	$229.20
Purchase #6	$188.64	11.600%	$210.5222	$210.52	$210.50	$210.50
Purchase #7	$198.80	11.604%	$221.8688	$221.87	$221.85	$221.90
7 purchase totals =	$988.23		$1,080.2474	$1,080.24	$1,080.15	$1,080.20