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	$161.40	12.736%	$181.9559	$181.96	$181.95	$182.00
Purchase #2	$168.45	12.121%	$188.8678	$188.87	$188.85	$188.90
Purchase #3	$58.62	5.503%	$61.8459	$61.85	$61.85	$61.80
Purchase #4	$199.94	7.564%	$215.0635	$215.06	$215.05	$215.10
Purchase #5	$57.27	13.800%	$65.1733	$65.17	$65.15	$65.20
Purchase #6	$125.67	13.635%	$142.8051	$142.81	$142.80	$142.80
Purchase #7	$190.33	8.225%	$205.9846	$205.98	$206.00	$206.00
7 purchase totals =	$961.68		$1,061.6961	$1,061.70	$1,061.65	$1,061.80