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	$65.52	10.409%	$72.34	$72.34	$72.35	$72.30
Purchase #2	$69.99	4.157%	$72.8995	$72.90	$72.90	$72.90
Purchase #3	$120.37	6.255%	$127.8991	$127.90	$127.90	$127.90
Purchase #4	$142.77	7.370%	$153.2921	$153.29	$153.30	$153.30
Purchase #5	$77.34	13.424%	$87.7221	$87.72	$87.70	$87.70
Purchase #6	$212.55	4.161%	$221.3942	$221.39	$221.40	$221.40
Purchase #7	$64.40	13.178%	$72.8866	$72.89	$72.90	$72.90
7 purchase totals =	$752.94		$808.4336	$808.43	$808.45	$808.40