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	$153.80	3.311%	$158.8923	$158.89	$158.90	$158.90
Purchase #2	$144.55	12.520%	$162.6477	$162.65	$162.65	$162.60
Purchase #3	$14.66	5.252%	$15.4299	$15.43	$15.45	$15.40
Purchase #4	$132.59	6.697%	$141.4696	$141.47	$141.45	$141.50
Purchase #5	$243.52	7.623%	$262.0835	$262.08	$262.10	$262.10
Purchase #6	$145.93	3.133%	$150.502	$150.50	$150.50	$150.50
Purchase #7	$128.70	10.496%	$142.2084	$142.21	$142.20	$142.20
7 purchase totals =	$963.75		$1,033.2334	$1,033.23	$1,033.25	$1,033.20