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	$192.82	6.652%	$205.6464	$205.65	$205.65	$205.60
Purchase #2	$178.37	7.337%	$191.457	$191.46	$191.45	$191.50
Purchase #3	$123.98	6.687%	$132.2705	$132.27	$132.25	$132.30
Purchase #4	$148.90	5.800%	$157.5362	$157.54	$157.55	$157.50
Purchase #5	$49.25	11.376%	$54.8527	$54.85	$54.85	$54.90
Purchase #6	$92.65	11.743%	$103.5299	$103.53	$103.55	$103.50
Purchase #7	$183.69	3.428%	$189.9869	$189.99	$190.00	$190.00
7 purchase totals =	$969.66		$1,035.2796	$1,035.29	$1,035.30	$1,035.30