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	$76.31	12.209%	$85.6267	$85.63	$85.65	$85.60
Purchase #2	$93.64	7.107%	$100.295	$100.30	$100.30	$100.30
Purchase #3	$53.64	10.330%	$59.181	$59.18	$59.20	$59.20
Purchase #4	$95.93	3.810%	$99.5849	$99.58	$99.60	$99.60
Purchase #5	$228.58	13.675%	$259.8383	$259.84	$259.85	$259.80
Purchase #6	$29.80	13.847%	$33.9264	$33.93	$33.95	$33.90
Purchase #7	$56.85	11.781%	$63.5475	$63.55	$63.55	$63.50
7 purchase totals =	$634.75		$701.9998	$702.01	$702.10	$701.90