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	$215.78	5.213%	$227.0286	$227.03	$227.05	$227.00
Purchase #2	$222.68	8.396%	$241.3762	$241.38	$241.40	$241.40
Purchase #3	$65.92	4.150%	$68.6557	$68.66	$68.65	$68.70
Purchase #4	$87.87	3.357%	$90.8198	$90.82	$90.80	$90.80
Purchase #5	$91.76	13.787%	$104.411	$104.41	$104.40	$104.40
Purchase #6	$98.39	13.250%	$111.4267	$111.43	$111.45	$111.40
Purchase #7	$173.99	13.506%	$197.4891	$197.49	$197.50	$197.50
7 purchase totals =	$956.39		$1,041.2071	$1,041.22	$1,041.25	$1,041.20