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	$191.34	4.388%	$199.736	$199.74	$199.75	$199.70
Purchase #2	$72.81	4.851%	$76.342	$76.34	$76.35	$76.30
Purchase #3	$232.57	5.682%	$245.7846	$245.78	$245.80	$245.80
Purchase #4	$98.79	6.383%	$105.0958	$105.10	$105.10	$105.10
Purchase #5	$101.58	5.418%	$107.0836	$107.08	$107.10	$107.10
Purchase #6	$56.98	4.406%	$59.4905	$59.49	$59.50	$59.50
Purchase #7	$97.85	6.221%	$103.9372	$103.94	$103.95	$103.90
7 purchase totals =	$851.92		$897.4697	$897.47	$897.55	$897.40