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	$65.55	10.772%	$72.611	$72.61	$72.60	$72.60
Purchase #2	$131.36	12.386%	$147.6302	$147.63	$147.65	$147.60
Purchase #3	$14.33	3.728%	$14.8642	$14.86	$14.85	$14.90
Purchase #4	$164.71	10.732%	$182.3867	$182.39	$182.40	$182.40
Purchase #5	$85.91	6.208%	$91.2433	$91.24	$91.25	$91.20
Purchase #6	$156.65	11.256%	$174.2825	$174.28	$174.30	$174.30
Purchase #7	$10.42	12.810%	$11.7548	$11.75	$11.75	$11.80
7 purchase totals =	$628.93		$694.7727	$694.76	$694.80	$694.80