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	$186.29	7.803%	$200.8262	$200.83	$200.85	$200.80
Purchase #2	$187.41	6.339%	$199.2899	$199.29	$199.30	$199.30
Purchase #3	$223.66	13.479%	$253.8071	$253.81	$253.80	$253.80
Purchase #4	$114.72	7.521%	$123.3481	$123.35	$123.35	$123.30
Purchase #5	$183.59	3.190%	$189.4465	$189.45	$189.45	$189.40
Purchase #6	$84.82	11.411%	$94.4988	$94.50	$94.50	$94.50
Purchase #7	$119.73	11.521%	$133.5241	$133.52	$133.50	$133.50
7 purchase totals =	$1,100.22		$1,194.7407	$1,194.75	$1,194.75	$1,194.60