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	$73.27	5.234%	$77.105	$77.11	$77.10	$77.10
Purchase #2	$53.87	13.318%	$61.0444	$61.04	$61.05	$61.00
Purchase #3	$99.32	10.731%	$109.978	$109.98	$110.00	$110.00
Purchase #4	$213.89	5.559%	$225.7801	$225.78	$225.80	$225.80
Purchase #5	$242.95	12.389%	$273.0491	$273.05	$273.05	$273.00
Purchase #6	$246.74	9.232%	$269.519	$269.52	$269.50	$269.50
Purchase #7	$65.85	7.229%	$70.6103	$70.61	$70.60	$70.60
7 purchase totals =	$995.89		$1,087.0859	$1,087.09	$1,087.10	$1,087.00