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	$118.66	7.478%	$127.5334	$127.53	$127.55	$127.50
Purchase #2	$41.33	6.107%	$43.854	$43.85	$43.85	$43.90
Purchase #3	$111.28	5.760%	$117.6897	$117.69	$117.70	$117.70
Purchase #4	$23.35	7.629%	$25.1314	$25.13	$25.15	$25.10
Purchase #5	$111.96	13.486%	$127.0589	$127.06	$127.05	$127.10
Purchase #6	$83.42	10.838%	$92.4611	$92.46	$92.45	$92.50
Purchase #7	$216.42	12.221%	$242.8687	$242.87	$242.85	$242.90
7 purchase totals =	$706.42		$776.5972	$776.59	$776.60	$776.70