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	$194.68	10.625%	$215.3648	$215.36	$215.35	$215.40
Purchase #2	$212.66	4.775%	$222.8145	$222.81	$222.80	$222.80
Purchase #3	$52.54	12.638%	$59.18	$59.18	$59.20	$59.20
Purchase #4	$104.64	11.337%	$116.503	$116.50	$116.50	$116.50
Purchase #5	$68.38	4.733%	$71.6164	$71.62	$71.60	$71.60
Purchase #6	$168.55	11.651%	$188.1878	$188.19	$188.20	$188.20
Purchase #7	$80.76	12.631%	$90.9608	$90.96	$90.95	$91.00
7 purchase totals =	$882.21		$964.6273	$964.62	$964.60	$964.70