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	$198.65	10.513%	$219.5341	$219.53	$219.55	$219.50
Purchase #2	$172.32	13.803%	$196.1053	$196.11	$196.10	$196.10
Purchase #3	$93.45	7.283%	$100.256	$100.26	$100.25	$100.30
Purchase #4	$129.27	11.780%	$144.498	$144.50	$144.50	$144.50
Purchase #5	$11.94	5.380%	$12.5824	$12.58	$12.60	$12.60
Purchase #6	$208.46	4.692%	$218.2409	$218.24	$218.25	$218.20
Purchase #7	$48.92	4.315%	$51.0309	$51.03	$51.05	$51.00
7 purchase totals =	$863.01		$942.2476	$942.25	$942.30	$942.20