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	$196.71	13.422%	$223.1124	$223.11	$223.10	$223.10
Purchase #2	$233.66	4.155%	$243.3686	$243.37	$243.35	$243.40
Purchase #3	$74.72	3.727%	$77.5048	$77.50	$77.50	$77.50
Purchase #4	$190.82	4.565%	$199.5309	$199.53	$199.55	$199.50
Purchase #5	$95.58	7.287%	$102.5449	$102.54	$102.55	$102.50
Purchase #6	$52.30	8.382%	$56.6838	$56.68	$56.70	$56.70
Purchase #7	$190.83	4.595%	$199.5986	$199.60	$199.60	$199.60
7 purchase totals =	$1,034.62		$1,102.3440	$1,102.33	$1,102.35	$1,102.30