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	$217.75	5.134%	$228.9293	$228.93	$228.95	$228.90
Purchase #2	$100.89	4.228%	$105.1556	$105.16	$105.15	$105.20
Purchase #3	$172.94	12.503%	$194.5627	$194.56	$194.55	$194.60
Purchase #4	$134.39	6.507%	$143.1348	$143.13	$143.15	$143.10
Purchase #5	$18.96	3.427%	$19.6098	$19.61	$19.60	$19.60
Purchase #6	$150.61	10.776%	$166.8397	$166.84	$166.85	$166.80
Purchase #7	$239.58	5.743%	$253.3391	$253.34	$253.35	$253.30
7 purchase totals =	$1,035.12		$1,111.5710	$1,111.57	$1,111.60	$1,111.50