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	$118.42	7.556%	$127.3678	$127.37	$127.35	$127.40
Purchase #2	$190.47	7.870%	$205.46	$205.46	$205.45	$205.50
Purchase #3	$137.95	11.506%	$153.8225	$153.82	$153.80	$153.80
Purchase #4	$236.33	5.492%	$249.3092	$249.31	$249.30	$249.30
Purchase #5	$75.74	12.515%	$85.2189	$85.22	$85.20	$85.20
Purchase #6	$191.33	12.138%	$214.5536	$214.55	$214.55	$214.60
Purchase #7	$56.56	10.778%	$62.656	$62.66	$62.65	$62.70
7 purchase totals =	$1,006.80		$1,098.3880	$1,098.39	$1,098.30	$1,098.50