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	$78.67	4.198%	$81.9726	$81.97	$81.95	$82.00
Purchase #2	$200.30	11.200%	$222.7336	$222.73	$222.75	$222.70
Purchase #3	$78.65	13.593%	$89.3409	$89.34	$89.35	$89.30
Purchase #4	$123.25	12.461%	$138.6082	$138.61	$138.60	$138.60
Purchase #5	$180.78	10.313%	$199.4238	$199.42	$199.40	$199.40
Purchase #6	$232.48	5.768%	$245.8894	$245.89	$245.90	$245.90
Purchase #7	$66.71	4.104%	$69.4478	$69.45	$69.45	$69.40
7 purchase totals =	$960.84		$1,047.4163	$1,047.41	$1,047.40	$1,047.30