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	$215.45	10.153%	$237.3246	$237.32	$237.30	$237.30
Purchase #2	$219.66	9.461%	$240.442	$240.44	$240.45	$240.40
Purchase #3	$111.27	4.749%	$116.5542	$116.55	$116.55	$116.60
Purchase #4	$61.86	7.543%	$66.5261	$66.53	$66.55	$66.50
Purchase #5	$94.93	10.562%	$104.9565	$104.96	$104.95	$105.00
Purchase #6	$159.65	8.173%	$172.6982	$172.70	$172.70	$172.70
Purchase #7	$75.32	12.852%	$85.0001	$85.00	$85.00	$85.00
7 purchase totals =	$938.14		$1,023.5017	$1,023.50	$1,023.50	$1,023.50