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	$198.81	8.375%	$215.4603	$215.46	$215.45	$215.50
Purchase #2	$34.88	4.205%	$36.3467	$36.35	$36.35	$36.30
Purchase #3	$22.27	10.371%	$24.5796	$24.58	$24.60	$24.60
Purchase #4	$36.60	13.184%	$41.4253	$41.43	$41.45	$41.40
Purchase #5	$196.42	11.757%	$219.5131	$219.51	$219.50	$219.50
Purchase #6	$249.53	12.568%	$280.8909	$280.89	$280.90	$280.90
Purchase #7	$154.78	9.541%	$169.5476	$169.55	$169.55	$169.50
7 purchase totals =	$893.29		$987.7635	$987.77	$987.80	$987.70