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	$224.47	4.662%	$234.9348	$234.93	$234.95	$234.90
Purchase #2	$101.55	11.164%	$112.887	$112.89	$112.90	$112.90
Purchase #3	$126.25	11.383%	$140.621	$140.62	$140.60	$140.60
Purchase #4	$238.84	5.243%	$251.3624	$251.36	$251.35	$251.40
Purchase #5	$93.43	10.397%	$103.1439	$103.14	$103.15	$103.10
Purchase #6	$240.30	10.526%	$265.594	$265.59	$265.60	$265.60
Purchase #7	$49.48	3.846%	$51.383	$51.38	$51.40	$51.40
7 purchase totals =	$1,074.32		$1,159.9261	$1,159.91	$1,159.95	$1,159.90