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	$231.33	10.563%	$255.7654	$255.77	$255.75	$255.80
Purchase #2	$23.45	7.696%	$25.2547	$25.25	$25.25	$25.30
Purchase #3	$21.81	12.347%	$24.5029	$24.50	$24.50	$24.50
Purchase #4	$217.51	10.723%	$240.8336	$240.83	$240.85	$240.80
Purchase #5	$151.50	11.392%	$168.7589	$168.76	$168.75	$168.80
Purchase #6	$97.34	7.595%	$104.733	$104.73	$104.75	$104.70
Purchase #7	$172.78	12.593%	$194.5382	$194.54	$194.55	$194.50
7 purchase totals =	$915.72		$1,014.3867	$1,014.38	$1,014.40	$1,014.40