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	$62.25	3.601%	$64.4916	$64.49	$64.50	$64.50
Purchase #2	$214.73	7.246%	$230.2893	$230.29	$230.30	$230.30
Purchase #3	$88.74	13.615%	$100.822	$100.82	$100.80	$100.80
Purchase #4	$197.41	11.675%	$220.4576	$220.46	$220.45	$220.50
Purchase #5	$173.25	4.815%	$181.592	$181.59	$181.60	$181.60
Purchase #6	$180.71	5.144%	$190.0057	$190.01	$190.00	$190.00
Purchase #7	$22.46	6.336%	$23.8831	$23.88	$23.90	$23.90
7 purchase totals =	$939.55		$1,011.5413	$1,011.54	$1,011.55	$1,011.60