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	$129.46	10.870%	$143.5323	$143.53	$143.55	$143.50
Purchase #2	$63.86	12.739%	$71.9951	$72.00	$72.00	$72.00
Purchase #3	$103.34	5.518%	$109.0423	$109.04	$109.05	$109.00
Purchase #4	$114.63	13.397%	$129.987	$129.99	$130.00	$130.00
Purchase #5	$17.27	10.530%	$19.0885	$19.09	$19.10	$19.10
Purchase #6	$134.36	13.423%	$152.3951	$152.40	$152.40	$152.40
Purchase #7	$160.97	7.158%	$172.4922	$172.49	$172.50	$172.50
7 purchase totals =	$723.89		$798.5325	$798.54	$798.60	$798.50