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	$169.89	9.771%	$186.49	$186.49	$186.50	$186.50
Purchase #2	$66.92	4.752%	$70.1	$70.10	$70.10	$70.10
Purchase #3	$209.81	8.268%	$227.1571	$227.16	$227.15	$227.20
Purchase #4	$165.67	3.522%	$171.5049	$171.50	$171.50	$171.50
Purchase #5	$38.70	10.233%	$42.6602	$42.66	$42.65	$42.70
Purchase #6	$124.47	4.698%	$130.3176	$130.32	$130.30	$130.30
Purchase #7	$182.93	4.497%	$191.1564	$191.16	$191.15	$191.20
7 purchase totals =	$958.39		$1,019.3862	$1,019.39	$1,019.35	$1,019.50