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	$196.32	9.791%	$215.5417	$215.54	$215.55	$215.50
Purchase #2	$52.96	6.514%	$56.4098	$56.41	$56.40	$56.40
Purchase #3	$223.93	10.748%	$247.998	$248.00	$248.00	$248.00
Purchase #4	$63.63	3.475%	$65.8411	$65.84	$65.85	$65.80
Purchase #5	$119.53	6.767%	$127.6186	$127.62	$127.60	$127.60
Purchase #6	$241.38	6.676%	$257.4945	$257.49	$257.50	$257.50
Purchase #7	$78.71	13.394%	$89.2524	$89.25	$89.25	$89.30
7 purchase totals =	$976.46		$1,060.1561	$1,060.15	$1,060.15	$1,060.10