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	$167.33	5.177%	$175.9927	$175.99	$176.00	$176.00
Purchase #2	$156.52	12.615%	$176.265	$176.27	$176.25	$176.30
Purchase #3	$247.88	7.154%	$265.6133	$265.61	$265.60	$265.60
Purchase #4	$136.77	4.280%	$142.6238	$142.62	$142.60	$142.60
Purchase #5	$176.29	5.312%	$185.6545	$185.65	$185.65	$185.70
Purchase #6	$63.71	13.155%	$72.0911	$72.09	$72.10	$72.10
Purchase #7	$29.43	5.486%	$31.0445	$31.04	$31.05	$31.00
7 purchase totals =	$977.93		$1,049.2849	$1,049.27	$1,049.25	$1,049.30