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	$92.70	4.501%	$96.8724	$96.87	$96.85	$96.90
Purchase #2	$108.80	9.123%	$118.7258	$118.73	$118.75	$118.70
Purchase #3	$24.87	4.272%	$25.9324	$25.93	$25.95	$25.90
Purchase #4	$32.44	8.129%	$35.077	$35.08	$35.10	$35.10
Purchase #5	$94.77	5.681%	$100.1539	$100.15	$100.15	$100.20
Purchase #6	$95.42	8.423%	$103.4572	$103.46	$103.45	$103.50
Purchase #7	$14.82	5.245%	$15.5973	$15.60	$15.60	$15.60
7 purchase totals =	$463.82		$495.8160	$495.82	$495.85	$495.90