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	$181.77	8.115%	$196.5206	$196.52	$196.50	$196.50
Purchase #2	$96.60	13.255%	$109.4043	$109.40	$109.40	$109.40
Purchase #3	$186.66	4.219%	$194.5352	$194.54	$194.55	$194.50
Purchase #4	$45.25	4.605%	$47.3338	$47.33	$47.35	$47.30
Purchase #5	$112.62	13.338%	$127.6413	$127.64	$127.65	$127.60
Purchase #6	$52.59	11.245%	$58.5037	$58.50	$58.50	$58.50
Purchase #7	$187.46	4.502%	$195.8994	$195.90	$195.90	$195.90
7 purchase totals =	$862.95		$929.8383	$929.83	$929.85	$929.70