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	$62.94	13.783%	$71.615	$71.62	$71.60	$71.60
Purchase #2	$182.31	7.467%	$195.9231	$195.92	$195.90	$195.90
Purchase #3	$101.36	4.119%	$105.535	$105.54	$105.55	$105.50
Purchase #4	$118.34	7.793%	$127.5622	$127.56	$127.55	$127.60
Purchase #5	$243.49	11.724%	$272.0368	$272.04	$272.05	$272.00
Purchase #6	$160.54	5.794%	$169.8417	$169.84	$169.85	$169.80
Purchase #7	$87.82	7.462%	$94.3731	$94.37	$94.35	$94.40
7 purchase totals =	$956.80		$1,036.8869	$1,036.89	$1,036.85	$1,036.80