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	$87.36	10.482%	$96.5171	$96.52	$96.50	$96.50
Purchase #2	$211.43	12.571%	$238.0089	$238.01	$238.00	$238.00
Purchase #3	$125.31	7.408%	$134.593	$134.59	$134.60	$134.60
Purchase #4	$105.65	10.390%	$116.627	$116.63	$116.65	$116.60
Purchase #5	$189.58	13.559%	$215.2852	$215.29	$215.30	$215.30
Purchase #6	$219.75	13.737%	$249.9371	$249.94	$249.95	$249.90
Purchase #7	$30.58	13.184%	$34.6117	$34.61	$34.60	$34.60
7 purchase totals =	$969.66		$1,085.5800	$1,085.59	$1,085.60	$1,085.50