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	$100.37	5.138%	$105.527	$105.53	$105.55	$105.50
Purchase #2	$17.30	11.353%	$19.2641	$19.26	$19.25	$19.30
Purchase #3	$214.48	11.682%	$239.5356	$239.54	$239.55	$239.50
Purchase #4	$148.29	4.401%	$154.8162	$154.82	$154.80	$154.80
Purchase #5	$125.44	10.303%	$138.3641	$138.36	$138.35	$138.40
Purchase #6	$106.27	3.220%	$109.6919	$109.69	$109.70	$109.70
Purchase #7	$238.28	4.770%	$249.646	$249.65	$249.65	$249.60
7 purchase totals =	$950.43		$1,016.8449	$1,016.85	$1,016.85	$1,016.80