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	$85.28	10.549%	$94.2762	$94.28	$94.30	$94.30
Purchase #2	$144.95	5.521%	$152.9527	$152.95	$152.95	$153.00
Purchase #3	$72.88	7.567%	$78.3948	$78.39	$78.40	$78.40
Purchase #4	$5.83	13.463%	$6.6149	$6.61	$6.60	$6.60
Purchase #5	$194.92	13.814%	$221.8462	$221.85	$221.85	$221.80
Purchase #6	$190.49	9.646%	$208.8647	$208.86	$208.85	$208.90
Purchase #7	$60.70	3.218%	$62.6533	$62.65	$62.65	$62.70
7 purchase totals =	$755.05		$825.6028	$825.59	$825.60	$825.70