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	$161.32	7.817%	$173.9304	$173.93	$173.95	$173.90
Purchase #2	$228.27	12.251%	$256.2354	$256.24	$256.25	$256.20
Purchase #3	$247.60	8.850%	$269.5126	$269.51	$269.50	$269.50
Purchase #4	$36.45	6.519%	$38.8262	$38.83	$38.85	$38.80
Purchase #5	$153.99	11.711%	$172.0238	$172.02	$172.00	$172.00
Purchase #6	$207.59	3.329%	$214.5007	$214.50	$214.50	$214.50
Purchase #7	$42.86	3.538%	$44.3764	$44.38	$44.40	$44.40
7 purchase totals =	$1,078.08		$1,169.4055	$1,169.41	$1,169.45	$1,169.30