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	$86.29	8.164%	$93.3347	$93.33	$93.35	$93.30
Purchase #2	$12.86	7.761%	$13.8581	$13.86	$13.85	$13.90
Purchase #3	$80.82	12.244%	$90.7156	$90.72	$90.70	$90.70
Purchase #4	$154.54	9.505%	$169.229	$169.23	$169.25	$169.20
Purchase #5	$85.94	10.130%	$94.6457	$94.65	$94.65	$94.60
Purchase #6	$81.85	4.320%	$85.3859	$85.39	$85.40	$85.40
Purchase #7	$16.52	5.564%	$17.4392	$17.44	$17.45	$17.40
7 purchase totals =	$518.82		$564.6082	$564.62	$564.65	$564.50