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	$214.47	4.481%	$224.0804	$224.08	$224.10	$224.10
Purchase #2	$214.40	3.551%	$222.0133	$222.01	$222.00	$222.00
Purchase #3	$119.79	6.718%	$127.8375	$127.84	$127.85	$127.80
Purchase #4	$169.75	6.628%	$181.001	$181.00	$181.00	$181.00
Purchase #5	$168.93	6.855%	$180.5102	$180.51	$180.50	$180.50
Purchase #6	$131.75	11.824%	$147.3281	$147.33	$147.35	$147.30
Purchase #7	$150.32	5.636%	$158.792	$158.79	$158.80	$158.80
7 purchase totals =	$1,169.41		$1,241.5625	$1,241.56	$1,241.60	$1,241.50