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	$112.52	10.161%	$123.9532	$123.95	$123.95	$124.00
Purchase #2	$212.33	13.712%	$241.4447	$241.44	$241.45	$241.40
Purchase #3	$67.53	4.842%	$70.7998	$70.80	$70.80	$70.80
Purchase #4	$83.77	3.144%	$86.4037	$86.40	$86.40	$86.40
Purchase #5	$199.47	7.491%	$214.4123	$214.41	$214.40	$214.40
Purchase #6	$238.32	7.763%	$256.8208	$256.82	$256.80	$256.80
Purchase #7	$40.35	13.769%	$45.9058	$45.91	$45.90	$45.90
7 purchase totals =	$954.29		$1,039.7403	$1,039.73	$1,039.70	$1,039.70