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	$55.41	11.247%	$61.642	$61.64	$61.65	$61.60
Purchase #2	$34.27	5.485%	$36.1497	$36.15	$36.15	$36.10
Purchase #3	$32.77	10.214%	$36.1171	$36.12	$36.10	$36.10
Purchase #4	$181.67	4.359%	$189.589	$189.59	$189.60	$189.60
Purchase #5	$103.49	4.513%	$108.1605	$108.16	$108.15	$108.20
Purchase #6	$64.84	10.484%	$71.6378	$71.64	$71.65	$71.60
Purchase #7	$196.76	9.713%	$215.8713	$215.87	$215.85	$215.90
7 purchase totals =	$669.21		$719.1674	$719.17	$719.15	$719.10