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	$229.55	6.265%	$243.9313	$243.93	$243.95	$243.90
Purchase #2	$206.72	4.282%	$215.5718	$215.57	$215.55	$215.60
Purchase #3	$28.25	5.460%	$29.7925	$29.79	$29.80	$29.80
Purchase #4	$80.50	6.162%	$85.4604	$85.46	$85.45	$85.50
Purchase #5	$182.48	9.646%	$200.082	$200.08	$200.10	$200.10
Purchase #6	$12.92	8.470%	$14.0143	$14.01	$14.00	$14.00
Purchase #7	$217.53	6.390%	$231.4302	$231.43	$231.45	$231.40
7 purchase totals =	$957.95		$1,020.2825	$1,020.27	$1,020.30	$1,020.30