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	$213.61	9.258%	$233.386	$233.39	$233.40	$233.40
Purchase #2	$64.32	11.351%	$71.621	$71.62	$71.60	$71.60
Purchase #3	$159.59	8.872%	$173.7488	$173.75	$173.75	$173.70
Purchase #4	$225.59	7.387%	$242.2543	$242.25	$242.25	$242.30
Purchase #5	$93.38	8.698%	$101.5022	$101.50	$101.50	$101.50
Purchase #6	$67.53	4.509%	$70.5749	$70.57	$70.55	$70.60
Purchase #7	$154.36	10.545%	$170.6373	$170.64	$170.65	$170.60
7 purchase totals =	$978.38		$1,063.7245	$1,063.72	$1,063.70	$1,063.70