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	$59.27	5.158%	$62.3271	$62.33	$62.35	$62.30
Purchase #2	$77.46	10.528%	$85.615	$85.62	$85.60	$85.60
Purchase #3	$170.29	12.752%	$192.0054	$192.01	$192.00	$192.00
Purchase #4	$142.82	10.777%	$158.2117	$158.21	$158.20	$158.20
Purchase #5	$190.38	10.745%	$210.8363	$210.84	$210.85	$210.80
Purchase #6	$170.64	10.842%	$189.1408	$189.14	$189.15	$189.10
Purchase #7	$187.67	10.469%	$207.3172	$207.32	$207.30	$207.30
7 purchase totals =	$998.53		$1,105.4535	$1,105.47	$1,105.45	$1,105.30