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	$162.78	9.584%	$178.3808	$178.38	$178.40	$178.40
Purchase #2	$180.93	9.611%	$198.3192	$198.32	$198.30	$198.30
Purchase #3	$57.48	12.293%	$64.546	$64.55	$64.55	$64.50
Purchase #4	$206.65	4.648%	$216.2551	$216.26	$216.25	$216.30
Purchase #5	$55.97	5.560%	$59.0819	$59.08	$59.10	$59.10
Purchase #6	$136.67	3.488%	$141.437	$141.44	$141.45	$141.40
Purchase #7	$147.95	7.125%	$158.4914	$158.49	$158.50	$158.50
7 purchase totals =	$948.43		$1,016.5114	$1,016.52	$1,016.55	$1,016.50