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	$103.96	8.670%	$112.9733	$112.97	$112.95	$113.00
Purchase #2	$19.28	12.715%	$21.7315	$21.73	$21.75	$21.70
Purchase #3	$89.92	4.307%	$93.7929	$93.79	$93.80	$93.80
Purchase #4	$65.97	13.574%	$74.9248	$74.92	$74.90	$74.90
Purchase #5	$82.75	8.261%	$89.586	$89.59	$89.60	$89.60
Purchase #6	$52.89	12.653%	$59.5822	$59.58	$59.60	$59.60
Purchase #7	$30.52	10.553%	$33.7408	$33.74	$33.75	$33.70
7 purchase totals =	$445.29		$486.3315	$486.32	$486.35	$486.30