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	$93.75	4.477%	$97.9472	$97.95	$97.95	$97.90
Purchase #2	$45.71	10.740%	$50.6193	$50.62	$50.60	$50.60
Purchase #3	$80.73	7.598%	$86.8639	$86.86	$86.85	$86.90
Purchase #4	$234.99	3.187%	$242.4791	$242.48	$242.50	$242.50
Purchase #5	$157.31	4.776%	$164.8231	$164.82	$164.80	$164.80
Purchase #6	$77.32	6.614%	$82.4339	$82.43	$82.45	$82.40
Purchase #7	$214.41	9.471%	$234.7168	$234.72	$234.70	$234.70
7 purchase totals =	$904.22		$959.8833	$959.88	$959.85	$959.80