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	$90.26	3.806%	$93.6953	$93.70	$93.70	$93.70
Purchase #2	$86.86	9.719%	$95.3019	$95.30	$95.30	$95.30
Purchase #3	$40.82	7.532%	$43.8946	$43.89	$43.90	$43.90
Purchase #4	$157.86	5.799%	$167.0143	$167.01	$167.00	$167.00
Purchase #5	$10.69	3.150%	$11.0267	$11.03	$11.05	$11.00
Purchase #6	$63.40	11.399%	$70.627	$70.63	$70.65	$70.60
Purchase #7	$162.64	11.796%	$181.825	$181.83	$181.85	$181.80
7 purchase totals =	$612.53		$663.3848	$663.39	$663.45	$663.30