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	$202.57	4.487%	$211.6593	$211.66	$211.65	$211.70
Purchase #2	$94.94	10.683%	$105.0824	$105.08	$105.10	$105.10
Purchase #3	$76.56	11.155%	$85.1003	$85.10	$85.10	$85.10
Purchase #4	$111.98	7.691%	$120.5924	$120.59	$120.60	$120.60
Purchase #5	$89.28	6.690%	$95.2528	$95.25	$95.25	$95.30
Purchase #6	$139.32	6.723%	$148.6865	$148.69	$148.70	$148.70
Purchase #7	$233.80	6.343%	$248.6299	$248.63	$248.65	$248.60
7 purchase totals =	$948.45		$1,015.0036	$1,015.00	$1,015.05	$1,015.10