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	$148.60	9.443%	$162.6323	$162.63	$162.65	$162.60
Purchase #2	$192.59	4.134%	$200.5517	$200.55	$200.55	$200.60
Purchase #3	$6.63	7.145%	$7.1037	$7.10	$7.10	$7.10
Purchase #4	$37.83	4.614%	$39.5755	$39.58	$39.60	$39.60
Purchase #5	$33.62	6.455%	$35.7902	$35.79	$35.80	$35.80
Purchase #6	$200.88	8.638%	$218.232	$218.23	$218.25	$218.20
Purchase #7	$85.79	4.771%	$89.883	$89.88	$89.90	$89.90
7 purchase totals =	$705.94		$753.7684	$753.76	$753.85	$753.80