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	$169.58	9.575%	$185.8173	$185.82	$185.80	$185.80
Purchase #2	$202.28	9.687%	$221.8749	$221.87	$221.85	$221.90
Purchase #3	$10.46	8.246%	$11.3225	$11.32	$11.30	$11.30
Purchase #4	$204.28	12.461%	$229.7353	$229.74	$229.75	$229.70
Purchase #5	$225.50	9.855%	$247.723	$247.72	$247.70	$247.70
Purchase #6	$237.83	7.375%	$255.37	$255.37	$255.35	$255.40
Purchase #7	$240.63	6.185%	$255.513	$255.51	$255.50	$255.50
7 purchase totals =	$1,290.56		$1,407.3560	$1,407.35	$1,407.25	$1,407.30