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	$41.69	4.336%	$43.4977	$43.50	$43.50	$43.50
Purchase #2	$62.89	3.369%	$65.0088	$65.01	$65.00	$65.00
Purchase #3	$174.49	8.283%	$188.943	$188.94	$188.95	$188.90
Purchase #4	$213.79	4.530%	$223.4747	$223.47	$223.45	$223.50
Purchase #5	$28.68	11.115%	$31.8678	$31.87	$31.85	$31.90
Purchase #6	$183.95	6.433%	$195.7835	$195.78	$195.80	$195.80
Purchase #7	$12.33	11.502%	$13.7482	$13.75	$13.75	$13.70
7 purchase totals =	$717.82		$762.3237	$762.32	$762.30	$762.30