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	$196.43	10.460%	$216.9766	$216.98	$217.00	$217.00
Purchase #2	$188.95	11.637%	$210.9381	$210.94	$210.95	$210.90
Purchase #3	$33.26	7.172%	$35.6454	$35.65	$35.65	$35.60
Purchase #4	$17.79	5.590%	$18.7845	$18.78	$18.80	$18.80
Purchase #5	$151.72	3.304%	$156.7328	$156.73	$156.75	$156.70
Purchase #6	$232.81	3.569%	$241.119	$241.12	$241.10	$241.10
Purchase #7	$93.81	4.817%	$98.3288	$98.33	$98.35	$98.30
7 purchase totals =	$914.77		$978.5252	$978.53	$978.60	$978.40