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	$61.59	11.535%	$68.6944	$68.69	$68.70	$68.70
Purchase #2	$157.47	3.271%	$162.6208	$162.62	$162.60	$162.60
Purchase #3	$169.68	6.361%	$180.4733	$180.47	$180.45	$180.50
Purchase #4	$185.32	6.255%	$196.9118	$196.91	$196.90	$196.90
Purchase #5	$172.69	11.530%	$192.6012	$192.60	$192.60	$192.60
Purchase #6	$113.32	12.200%	$127.145	$127.15	$127.15	$127.10
Purchase #7	$15.90	5.804%	$16.8228	$16.82	$16.80	$16.80
7 purchase totals =	$875.97		$945.2693	$945.26	$945.20	$945.20