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	$98.45	9.561%	$107.8628	$107.86	$107.85	$107.90
Purchase #2	$123.52	3.399%	$127.7184	$127.72	$127.70	$127.70
Purchase #3	$81.25	6.547%	$86.5694	$86.57	$86.55	$86.60
Purchase #4	$211.93	10.147%	$233.4345	$233.43	$233.45	$233.40
Purchase #5	$130.36	11.437%	$145.2693	$145.27	$145.25	$145.30
Purchase #6	$139.95	6.714%	$149.3462	$149.35	$149.35	$149.30
Purchase #7	$156.36	6.327%	$166.2529	$166.25	$166.25	$166.30
7 purchase totals =	$941.82		$1,016.4535	$1,016.45	$1,016.40	$1,016.50