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	$62.95	12.162%	$70.606	$70.61	$70.60	$70.60
Purchase #2	$206.55	7.609%	$222.2664	$222.27	$222.25	$222.30
Purchase #3	$164.68	9.424%	$180.1994	$180.20	$180.20	$180.20
Purchase #4	$149.40	10.820%	$165.5651	$165.57	$165.55	$165.60
Purchase #5	$143.87	11.589%	$160.5431	$160.54	$160.55	$160.50
Purchase #6	$61.79	4.454%	$64.5421	$64.54	$64.55	$64.50
Purchase #7	$189.40	4.526%	$197.9722	$197.97	$197.95	$198.00
7 purchase totals =	$978.64		$1,061.6943	$1,061.70	$1,061.65	$1,061.70