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	$148.69	9.203%	$162.3739	$162.37	$162.35	$162.40
Purchase #2	$95.25	6.843%	$101.768	$101.77	$101.75	$101.80
Purchase #3	$82.27	9.817%	$90.3464	$90.35	$90.35	$90.30
Purchase #4	$20.76	4.249%	$21.6421	$21.64	$21.65	$21.60
Purchase #5	$249.53	13.220%	$282.5179	$282.52	$282.50	$282.50
Purchase #6	$196.95	11.489%	$219.5776	$219.58	$219.60	$219.60
Purchase #7	$77.56	8.724%	$84.3263	$84.33	$84.35	$84.30
7 purchase totals =	$871.01		$962.5522	$962.56	$962.55	$962.50