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	$38.64	13.751%	$43.9534	$43.95	$43.95	$44.00
Purchase #2	$57.30	4.708%	$59.9977	$60.00	$60.00	$60.00
Purchase #3	$33.33	12.431%	$37.4733	$37.47	$37.45	$37.50
Purchase #4	$35.95	4.796%	$37.6742	$37.67	$37.65	$37.70
Purchase #5	$163.57	3.520%	$169.3277	$169.33	$169.35	$169.30
Purchase #6	$7.89	5.551%	$8.328	$8.33	$8.35	$8.30
Purchase #7	$165.99	9.386%	$181.5698	$181.57	$181.55	$181.60
7 purchase totals =	$502.67		$538.3241	$538.32	$538.30	$538.40