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	$196.99	4.432%	$205.7206	$205.72	$205.70	$205.70
Purchase #2	$32.69	4.175%	$34.0548	$34.05	$34.05	$34.10
Purchase #3	$53.78	10.112%	$59.2182	$59.22	$59.20	$59.20
Purchase #4	$131.71	10.369%	$145.367	$145.37	$145.35	$145.40
Purchase #5	$96.59	5.425%	$101.83	$101.83	$101.85	$101.80
Purchase #6	$14.79	3.392%	$15.2917	$15.29	$15.30	$15.30
Purchase #7	$6.99	5.152%	$7.3501	$7.35	$7.35	$7.40
7 purchase totals =	$533.54		$568.8324	$568.83	$568.80	$568.90