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	$188.32	4.384%	$196.5759	$196.58	$196.60	$196.60
Purchase #2	$248.52	3.369%	$256.8926	$256.89	$256.90	$256.90
Purchase #3	$236.31	4.833%	$247.7309	$247.73	$247.75	$247.70
Purchase #4	$60.74	8.321%	$65.7942	$65.79	$65.80	$65.80
Purchase #5	$114.48	5.269%	$120.512	$120.51	$120.50	$120.50
Purchase #6	$31.83	10.245%	$35.091	$35.09	$35.10	$35.10
Purchase #7	$130.72	5.856%	$138.375	$138.38	$138.40	$138.40
7 purchase totals =	$1,010.92		$1,060.9716	$1,060.97	$1,061.05	$1,061.00