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	$163.96	9.385%	$179.3476	$179.35	$179.35	$179.30
Purchase #2	$229.78	10.183%	$253.1785	$253.18	$253.20	$253.20
Purchase #3	$151.28	13.333%	$171.4502	$171.45	$171.45	$171.50
Purchase #4	$166.93	13.791%	$189.9513	$189.95	$189.95	$190.00
Purchase #5	$88.67	10.611%	$98.0788	$98.08	$98.10	$98.10
Purchase #6	$139.47	5.650%	$147.3501	$147.35	$147.35	$147.40
Purchase #7	$11.67	6.803%	$12.4639	$12.46	$12.45	$12.50
7 purchase totals =	$951.76		$1,051.8204	$1,051.82	$1,051.85	$1,052.00