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	$79.72	3.446%	$82.4672	$82.47	$82.45	$82.50
Purchase #2	$11.47	8.108%	$12.4	$12.40	$12.40	$12.40
Purchase #3	$78.99	5.112%	$83.028	$83.03	$83.05	$83.00
Purchase #4	$73.59	10.177%	$81.0793	$81.08	$81.10	$81.10
Purchase #5	$144.63	9.301%	$158.082	$158.08	$158.10	$158.10
Purchase #6	$31.56	13.710%	$35.8869	$35.89	$35.90	$35.90
Purchase #7	$14.33	11.382%	$15.961	$15.96	$15.95	$16.00
7 purchase totals =	$434.29		$468.9044	$468.91	$468.95	$469.00