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	$100.47	4.483%	$104.9741	$104.97	$104.95	$105.00
Purchase #2	$147.60	4.149%	$153.7239	$153.72	$153.70	$153.70
Purchase #3	$198.47	13.845%	$225.9482	$225.95	$225.95	$225.90
Purchase #4	$180.60	5.454%	$190.4499	$190.45	$190.45	$190.40
Purchase #5	$13.39	8.256%	$14.4955	$14.50	$14.50	$14.50
Purchase #6	$230.83	8.428%	$250.2844	$250.28	$250.30	$250.30
Purchase #7	$72.67	5.665%	$76.7868	$76.79	$76.80	$76.80
7 purchase totals =	$944.03		$1,016.6628	$1,016.66	$1,016.65	$1,016.60