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	$195.85	8.215%	$211.9391	$211.94	$211.95	$211.90
Purchase #2	$97.46	8.546%	$105.7889	$105.79	$105.80	$105.80
Purchase #3	$94.97	7.586%	$102.1744	$102.17	$102.15	$102.20
Purchase #4	$93.49	12.368%	$105.0528	$105.05	$105.05	$105.10
Purchase #5	$17.61	6.278%	$18.7156	$18.72	$18.70	$18.70
Purchase #6	$200.31	9.760%	$219.8603	$219.86	$219.85	$219.90
Purchase #7	$105.45	6.148%	$111.9331	$111.93	$111.95	$111.90
7 purchase totals =	$805.14		$875.4642	$875.46	$875.45	$875.50