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	$214.55	5.823%	$227.0432	$227.04	$227.05	$227.00
Purchase #2	$200.56	5.780%	$212.1524	$212.15	$212.15	$212.20
Purchase #3	$64.74	3.514%	$67.015	$67.02	$67.00	$67.00
Purchase #4	$165.68	10.751%	$183.4923	$183.49	$183.50	$183.50
Purchase #5	$176.85	7.700%	$190.4675	$190.47	$190.45	$190.50
Purchase #6	$59.76	4.386%	$62.3811	$62.38	$62.40	$62.40
Purchase #7	$63.39	3.600%	$65.672	$65.67	$65.65	$65.70
7 purchase totals =	$945.53		$1,008.2235	$1,008.22	$1,008.20	$1,008.30