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	$60.37	5.622%	$63.764	$63.76	$63.75	$63.80
Purchase #2	$79.55	4.677%	$83.2706	$83.27	$83.25	$83.30
Purchase #3	$89.81	13.530%	$101.9613	$101.96	$101.95	$102.00
Purchase #4	$48.93	9.116%	$53.3905	$53.39	$53.40	$53.40
Purchase #5	$42.27	11.216%	$47.011	$47.01	$47.00	$47.00
Purchase #6	$100.68	4.374%	$105.0837	$105.08	$105.10	$105.10
Purchase #7	$76.64	5.788%	$81.0759	$81.08	$81.10	$81.10
7 purchase totals =	$498.25		$535.5570	$535.55	$535.55	$535.70