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	$174.91	11.434%	$194.9092	$194.91	$194.90	$194.90
Purchase #2	$73.47	7.643%	$79.0853	$79.09	$79.10	$79.10
Purchase #3	$85.86	5.659%	$90.7188	$90.72	$90.70	$90.70
Purchase #4	$20.50	5.155%	$21.5568	$21.56	$21.55	$21.60
Purchase #5	$67.39	7.256%	$72.2798	$72.28	$72.30	$72.30
Purchase #6	$80.87	6.771%	$86.3457	$86.35	$86.35	$86.30
Purchase #7	$164.95	8.113%	$178.3324	$178.33	$178.35	$178.30
7 purchase totals =	$667.95		$723.2280	$723.24	$723.25	$723.20