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	$196.38	10.688%	$217.3691	$217.37	$217.35	$217.40
Purchase #2	$144.76	7.328%	$155.368	$155.37	$155.35	$155.40
Purchase #3	$122.82	4.129%	$127.8912	$127.89	$127.90	$127.90
Purchase #4	$215.53	4.584%	$225.4099	$225.41	$225.40	$225.40
Purchase #5	$50.97	4.495%	$53.2611	$53.26	$53.25	$53.30
Purchase #6	$57.52	8.259%	$62.2706	$62.27	$62.25	$62.30
Purchase #7	$236.83	5.796%	$250.5567	$250.56	$250.55	$250.60
7 purchase totals =	$1,024.81		$1,092.1266	$1,092.13	$1,092.05	$1,092.30