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	$194.64	11.217%	$216.4728	$216.47	$216.45	$216.50
Purchase #2	$144.25	6.788%	$154.0417	$154.04	$154.05	$154.00
Purchase #3	$99.77	10.159%	$109.9056	$109.91	$109.90	$109.90
Purchase #4	$184.91	4.348%	$192.9499	$192.95	$192.95	$192.90
Purchase #5	$160.93	4.761%	$168.5919	$168.59	$168.60	$168.60
Purchase #6	$13.68	7.402%	$14.6926	$14.69	$14.70	$14.70
Purchase #7	$243.91	4.405%	$254.6542	$254.65	$254.65	$254.70
7 purchase totals =	$1,042.09		$1,111.3087	$1,111.30	$1,111.30	$1,111.30