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	$197.39	13.721%	$224.4739	$224.47	$224.45	$224.50
Purchase #2	$53.41	3.820%	$55.4503	$55.45	$55.45	$55.50
Purchase #3	$103.41	7.361%	$111.022	$111.02	$111.00	$111.00
Purchase #4	$113.68	11.296%	$126.5213	$126.52	$126.50	$126.50
Purchase #5	$198.90	5.157%	$209.1573	$209.16	$209.15	$209.20
Purchase #6	$133.98	7.841%	$144.4854	$144.49	$144.50	$144.50
Purchase #7	$200.44	12.266%	$225.026	$225.03	$225.05	$225.00
7 purchase totals =	$1,001.21		$1,096.1362	$1,096.14	$1,096.10	$1,096.20