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	$13.46	7.756%	$14.504	$14.50	$14.50	$14.50
Purchase #2	$33.51	8.852%	$36.4763	$36.48	$36.50	$36.50
Purchase #3	$66.38	12.818%	$74.8886	$74.89	$74.90	$74.90
Purchase #4	$31.51	6.198%	$33.463	$33.46	$33.45	$33.50
Purchase #5	$11.77	6.724%	$12.5614	$12.56	$12.55	$12.60
Purchase #6	$35.51	4.724%	$37.1875	$37.19	$37.20	$37.20
Purchase #7	$240.92	4.494%	$251.7469	$251.75	$251.75	$251.70
7 purchase totals =	$433.06		$460.8277	$460.83	$460.85	$460.90