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	$114.91	11.170%	$127.7454	$127.75	$127.75	$127.70
Purchase #2	$60.37	5.724%	$63.8256	$63.83	$63.85	$63.80
Purchase #3	$21.39	13.707%	$24.3219	$24.32	$24.30	$24.30
Purchase #4	$182.43	9.639%	$200.0144	$200.01	$200.00	$200.00
Purchase #5	$98.95	6.810%	$105.6885	$105.69	$105.70	$105.70
Purchase #6	$157.91	10.740%	$174.8695	$174.87	$174.85	$174.90
Purchase #7	$157.60	13.606%	$179.0431	$179.04	$179.05	$179.00
7 purchase totals =	$793.56		$875.5084	$875.51	$875.50	$875.40