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	$192.57	11.667%	$215.0371	$215.04	$215.05	$215.00
Purchase #2	$68.72	10.588%	$75.9961	$76.00	$76.00	$76.00
Purchase #3	$61.25	6.738%	$65.377	$65.38	$65.40	$65.40
Purchase #4	$55.86	6.653%	$59.5764	$59.58	$59.60	$59.60
Purchase #5	$238.64	12.772%	$269.1191	$269.12	$269.10	$269.10
Purchase #6	$67.31	5.230%	$70.8303	$70.83	$70.85	$70.80
Purchase #7	$230.67	11.699%	$257.6561	$257.66	$257.65	$257.70
7 purchase totals =	$915.02		$1,013.5921	$1,013.61	$1,013.65	$1,013.60