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	$161.44	3.797%	$167.5699	$167.57	$167.55	$167.60
Purchase #2	$9.87	4.244%	$10.2889	$10.29	$10.30	$10.30
Purchase #3	$100.52	9.343%	$109.9116	$109.91	$109.90	$109.90
Purchase #4	$155.44	3.584%	$161.011	$161.01	$161.00	$161.00
Purchase #5	$160.34	13.478%	$181.9506	$181.95	$181.95	$182.00
Purchase #6	$94.50	13.779%	$107.5212	$107.52	$107.50	$107.50
Purchase #7	$76.61	7.448%	$82.3159	$82.32	$82.30	$82.30
7 purchase totals =	$758.72		$820.5691	$820.57	$820.50	$820.60