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	$215.76	8.402%	$233.8882	$233.89	$233.90	$233.90
Purchase #2	$190.42	3.487%	$197.0599	$197.06	$197.05	$197.10
Purchase #3	$74.74	10.195%	$82.3597	$82.36	$82.35	$82.40
Purchase #4	$94.48	4.243%	$98.4888	$98.49	$98.50	$98.50
Purchase #5	$136.52	3.344%	$141.0852	$141.09	$141.10	$141.10
Purchase #6	$188.33	9.601%	$206.4116	$206.41	$206.40	$206.40
Purchase #7	$77.86	11.246%	$86.6161	$86.62	$86.60	$86.60
7 purchase totals =	$978.11		$1,045.9095	$1,045.92	$1,045.90	$1,046.00