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	$101.85	9.578%	$111.6052	$111.61	$111.60	$111.60
Purchase #2	$72.42	7.588%	$77.9152	$77.92	$77.90	$77.90
Purchase #3	$81.59	4.338%	$85.1294	$85.13	$85.15	$85.10
Purchase #4	$114.25	8.378%	$123.8219	$123.82	$123.80	$123.80
Purchase #5	$141.93	7.396%	$152.4271	$152.43	$152.45	$152.40
Purchase #6	$149.78	7.163%	$160.5087	$160.51	$160.50	$160.50
Purchase #7	$204.46	4.534%	$213.7302	$213.73	$213.75	$213.70
7 purchase totals =	$866.28		$925.1377	$925.15	$925.15	$925.00