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	$191.64	11.681%	$214.0255	$214.03	$214.05	$214.00
Purchase #2	$110.38	5.405%	$116.346	$116.35	$116.35	$116.30
Purchase #3	$212.39	9.838%	$233.2849	$233.28	$233.30	$233.30
Purchase #4	$89.64	4.702%	$93.8549	$93.85	$93.85	$93.90
Purchase #5	$183.67	6.739%	$196.0475	$196.05	$196.05	$196.00
Purchase #6	$145.38	5.587%	$153.5024	$153.50	$153.50	$153.50
Purchase #7	$77.97	7.119%	$83.5207	$83.52	$83.50	$83.50
7 purchase totals =	$1,011.07		$1,090.5819	$1,090.58	$1,090.60	$1,090.50