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	$13.96	3.511%	$14.4501	$14.45	$14.45	$14.50
Purchase #2	$29.91	11.338%	$33.3012	$33.30	$33.30	$33.30
Purchase #3	$53.44	11.466%	$59.5674	$59.57	$59.55	$59.60
Purchase #4	$174.61	4.388%	$182.2719	$182.27	$182.25	$182.30
Purchase #5	$206.68	13.164%	$233.8874	$233.89	$233.90	$233.90
Purchase #6	$131.56	6.269%	$139.8075	$139.81	$139.80	$139.80
Purchase #7	$23.34	5.752%	$24.6825	$24.68	$24.70	$24.70
7 purchase totals =	$633.50		$687.9680	$687.97	$687.95	$688.10