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	$198.41	9.751%	$217.757	$217.76	$217.75	$217.80
Purchase #2	$84.35	7.701%	$90.8458	$90.85	$90.85	$90.80
Purchase #3	$105.63	4.395%	$110.2724	$110.27	$110.25	$110.30
Purchase #4	$212.40	7.844%	$229.0607	$229.06	$229.05	$229.10
Purchase #5	$162.79	10.365%	$179.6632	$179.66	$179.65	$179.70
Purchase #6	$139.35	8.587%	$151.316	$151.32	$151.30	$151.30
Purchase #7	$121.68	4.858%	$127.5912	$127.59	$127.60	$127.60
7 purchase totals =	$1,024.61		$1,106.5063	$1,106.51	$1,106.45	$1,106.60