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	$188.82	6.115%	$200.3663	$200.37	$200.35	$200.40
Purchase #2	$86.72	6.381%	$92.2536	$92.25	$92.25	$92.30
Purchase #3	$247.43	3.544%	$256.1989	$256.20	$256.20	$256.20
Purchase #4	$204.99	3.703%	$212.5808	$212.58	$212.60	$212.60
Purchase #5	$93.50	6.822%	$99.8786	$99.88	$99.90	$99.90
Purchase #6	$24.55	11.588%	$27.3949	$27.39	$27.40	$27.40
Purchase #7	$187.43	6.794%	$200.164	$200.16	$200.15	$200.20
7 purchase totals =	$1,033.44		$1,088.8371	$1,088.83	$1,088.85	$1,089.00