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	$86.78	10.185%	$95.6185	$95.62	$95.60	$95.60
Purchase #2	$242.60	5.260%	$255.3608	$255.36	$255.35	$255.40
Purchase #3	$189.84	4.340%	$198.0791	$198.08	$198.10	$198.10
Purchase #4	$115.93	4.799%	$121.4935	$121.49	$121.50	$121.50
Purchase #5	$74.64	4.606%	$78.0779	$78.08	$78.10	$78.10
Purchase #6	$65.51	6.786%	$69.9555	$69.96	$69.95	$70.00
Purchase #7	$229.92	11.136%	$255.5239	$255.52	$255.50	$255.50
7 purchase totals =	$1,005.22		$1,074.1092	$1,074.11	$1,074.10	$1,074.20