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	$152.64	4.868%	$160.0705	$160.07	$160.05	$160.10
Purchase #2	$115.37	9.429%	$126.2482	$126.25	$126.25	$126.20
Purchase #3	$209.75	11.390%	$233.6405	$233.64	$233.65	$233.60
Purchase #4	$119.87	5.476%	$126.4341	$126.43	$126.45	$126.40
Purchase #5	$54.29	9.641%	$59.5241	$59.52	$59.50	$59.50
Purchase #6	$235.61	4.691%	$246.6625	$246.66	$246.65	$246.70
Purchase #7	$196.52	8.626%	$213.4718	$213.47	$213.45	$213.50
7 purchase totals =	$1,084.05		$1,166.0517	$1,166.04	$1,166.00	$1,166.00