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	$186.26	10.404%	$205.6385	$205.64	$205.65	$205.60
Purchase #2	$236.58	11.356%	$263.446	$263.45	$263.45	$263.40
Purchase #3	$239.37	7.146%	$256.4754	$256.48	$256.50	$256.50
Purchase #4	$152.87	12.260%	$171.6119	$171.61	$171.60	$171.60
Purchase #5	$227.98	11.236%	$253.5958	$253.60	$253.60	$253.60
Purchase #6	$148.69	13.366%	$168.5639	$168.56	$168.55	$168.60
Purchase #7	$151.64	8.677%	$164.7978	$164.80	$164.80	$164.80
7 purchase totals =	$1,343.39		$1,484.1293	$1,484.14	$1,484.15	$1,484.10