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	$103.77	7.693%	$111.753	$111.75	$111.75	$111.80
Purchase #2	$10.83	4.473%	$11.3144	$11.31	$11.30	$11.30
Purchase #3	$223.64	3.485%	$231.4339	$231.43	$231.45	$231.40
Purchase #4	$170.27	6.647%	$181.5878	$181.59	$181.60	$181.60
Purchase #5	$119.50	3.309%	$123.4543	$123.45	$123.45	$123.50
Purchase #6	$227.57	10.393%	$251.2214	$251.22	$251.20	$251.20
Purchase #7	$152.56	6.830%	$162.9798	$162.98	$163.00	$163.00
7 purchase totals =	$1,008.14		$1,073.7446	$1,073.73	$1,073.75	$1,073.80