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	$213.74	9.346%	$233.7161	$233.72	$233.70	$233.70
Purchase #2	$81.52	6.113%	$86.5033	$86.50	$86.50	$86.50
Purchase #3	$142.47	13.781%	$162.1038	$162.10	$162.10	$162.10
Purchase #4	$112.78	12.274%	$126.6226	$126.62	$126.60	$126.60
Purchase #5	$94.48	4.746%	$98.964	$98.96	$98.95	$99.00
Purchase #6	$111.32	12.387%	$125.1092	$125.11	$125.10	$125.10
Purchase #7	$93.67	7.543%	$100.7355	$100.74	$100.75	$100.70
7 purchase totals =	$849.98		$933.7545	$933.75	$933.70	$933.70