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	$109.59	6.344%	$116.5424	$116.54	$116.55	$116.50
Purchase #2	$62.62	6.450%	$66.659	$66.66	$66.65	$66.70
Purchase #3	$12.52	5.679%	$13.231	$13.23	$13.25	$13.20
Purchase #4	$64.73	10.664%	$71.6328	$71.63	$71.65	$71.60
Purchase #5	$31.61	6.503%	$33.6656	$33.67	$33.65	$33.70
Purchase #6	$222.74	6.651%	$237.5544	$237.55	$237.55	$237.60
Purchase #7	$168.46	11.615%	$188.0266	$188.03	$188.05	$188.00
7 purchase totals =	$672.27		$727.3118	$727.31	$727.35	$727.30