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	$130.78	8.380%	$141.7394	$141.74	$141.75	$141.70
Purchase #2	$183.42	7.136%	$196.5089	$196.51	$196.50	$196.50
Purchase #3	$231.85	8.224%	$250.9173	$250.92	$250.90	$250.90
Purchase #4	$136.26	5.455%	$143.693	$143.69	$143.70	$143.70
Purchase #5	$55.66	3.432%	$57.5703	$57.57	$57.55	$57.60
Purchase #6	$73.70	3.745%	$76.4601	$76.46	$76.45	$76.50
Purchase #7	$188.39	6.275%	$200.2115	$200.21	$200.20	$200.20
7 purchase totals =	$1,000.06		$1,067.1005	$1,067.10	$1,067.05	$1,067.10