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	$161.43	6.873%	$172.5251	$172.53	$172.55	$172.50
Purchase #2	$131.75	5.575%	$139.0951	$139.10	$139.10	$139.10
Purchase #3	$56.30	5.832%	$59.5834	$59.58	$59.60	$59.60
Purchase #4	$145.48	11.286%	$161.8989	$161.90	$161.90	$161.90
Purchase #5	$225.94	13.411%	$256.2408	$256.24	$256.25	$256.20
Purchase #6	$74.90	5.419%	$78.9588	$78.96	$78.95	$79.00
Purchase #7	$222.64	7.394%	$239.102	$239.10	$239.10	$239.10
7 purchase totals =	$1,018.44		$1,107.4041	$1,107.41	$1,107.45	$1,107.40