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	$97.25	8.505%	$105.5211	$105.52	$105.50	$105.50
Purchase #2	$137.69	9.685%	$151.0253	$151.03	$151.05	$151.00
Purchase #3	$231.44	7.826%	$249.5525	$249.55	$249.55	$249.60
Purchase #4	$71.59	10.239%	$78.9201	$78.92	$78.90	$78.90
Purchase #5	$139.66	8.454%	$151.4669	$151.47	$151.45	$151.50
Purchase #6	$141.78	10.243%	$156.3025	$156.30	$156.30	$156.30
Purchase #7	$110.28	11.851%	$123.3493	$123.35	$123.35	$123.30
7 purchase totals =	$929.69		$1,016.1377	$1,016.14	$1,016.10	$1,016.10