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	$112.50	3.372%	$116.2935	$116.29	$116.30	$116.30
Purchase #2	$93.28	5.600%	$98.5037	$98.50	$98.50	$98.50
Purchase #3	$109.64	11.783%	$122.5589	$122.56	$122.55	$122.60
Purchase #4	$216.98	3.523%	$224.6242	$224.62	$224.60	$224.60
Purchase #5	$128.29	4.364%	$133.8886	$133.89	$133.90	$133.90
Purchase #6	$183.26	4.164%	$190.8909	$190.89	$190.90	$190.90
Purchase #7	$164.95	9.833%	$181.1695	$181.17	$181.15	$181.20
7 purchase totals =	$1,008.90		$1,067.9293	$1,067.92	$1,067.90	$1,068.00