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	$133.26	9.249%	$145.5852	$145.59	$145.60	$145.60
Purchase #2	$219.60	12.685%	$247.4563	$247.46	$247.45	$247.50
Purchase #3	$57.83	4.767%	$60.5868	$60.59	$60.60	$60.60
Purchase #4	$207.54	4.852%	$217.6098	$217.61	$217.60	$217.60
Purchase #5	$139.32	11.502%	$155.3446	$155.34	$155.35	$155.30
Purchase #6	$192.86	4.191%	$200.9428	$200.94	$200.95	$200.90
Purchase #7	$44.41	5.718%	$46.9494	$46.95	$46.95	$46.90
7 purchase totals =	$994.82		$1,074.4749	$1,074.48	$1,074.50	$1,074.40