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	$197.79	5.425%	$208.5201	$208.52	$208.50	$208.50
Purchase #2	$29.26	8.298%	$31.688	$31.69	$31.70	$31.70
Purchase #3	$72.55	13.669%	$82.4669	$82.47	$82.45	$82.50
Purchase #4	$250.96	6.521%	$267.3251	$267.33	$267.35	$267.30
Purchase #5	$60.30	9.315%	$65.9169	$65.92	$65.90	$65.90
Purchase #6	$181.60	8.389%	$196.8344	$196.83	$196.85	$196.80
Purchase #7	$151.63	8.172%	$164.0212	$164.02	$164.00	$164.00
7 purchase totals =	$944.09		$1,016.7726	$1,016.78	$1,016.75	$1,016.70