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	$64.26	12.763%	$72.4615	$72.46	$72.45	$72.50
Purchase #2	$31.90	13.152%	$36.0955	$36.10	$36.10	$36.10
Purchase #3	$92.92	13.134%	$105.1241	$105.12	$105.10	$105.10
Purchase #4	$11.37	5.264%	$11.9685	$11.97	$11.95	$12.00
Purchase #5	$53.47	7.685%	$57.5792	$57.58	$57.60	$57.60
Purchase #6	$100.62	4.436%	$105.0835	$105.08	$105.10	$105.10
Purchase #7	$52.72	11.346%	$58.7016	$58.70	$58.70	$58.70
7 purchase totals =	$407.26		$447.0139	$447.01	$447.00	$447.10