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	$215.46	3.124%	$222.191	$222.19	$222.20	$222.20
Purchase #2	$140.73	12.627%	$158.5	$158.50	$158.50	$158.50
Purchase #3	$137.87	3.858%	$143.189	$143.19	$143.20	$143.20
Purchase #4	$48.95	6.708%	$52.2336	$52.23	$52.25	$52.20
Purchase #5	$171.28	5.240%	$180.2551	$180.26	$180.25	$180.30
Purchase #6	$210.74	9.581%	$230.931	$230.93	$230.95	$230.90
Purchase #7	$156.73	13.681%	$178.1722	$178.17	$178.15	$178.20
7 purchase totals =	$1,081.76		$1,165.4719	$1,165.47	$1,165.50	$1,165.50