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	$148.64	3.491%	$153.829	$153.83	$153.85	$153.80
Purchase #2	$51.90	3.234%	$53.5784	$53.58	$53.60	$53.60
Purchase #3	$18.35	9.400%	$20.0749	$20.07	$20.05	$20.10
Purchase #4	$31.50	12.824%	$35.5396	$35.54	$35.55	$35.50
Purchase #5	$135.46	13.293%	$153.4667	$153.47	$153.45	$153.50
Purchase #6	$126.41	8.870%	$137.6226	$137.62	$137.60	$137.60
Purchase #7	$199.89	11.868%	$223.6129	$223.61	$223.60	$223.60
7 purchase totals =	$712.15		$777.7241	$777.72	$777.70	$777.70