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	$196.93	5.700%	$208.155	$208.16	$208.15	$208.20
Purchase #2	$192.27	4.325%	$200.5857	$200.59	$200.60	$200.60
Purchase #3	$72.79	13.152%	$82.3633	$82.36	$82.35	$82.40
Purchase #4	$194.42	9.414%	$212.7227	$212.72	$212.70	$212.70
Purchase #5	$160.60	3.822%	$166.7381	$166.74	$166.75	$166.70
Purchase #6	$114.84	11.191%	$127.6917	$127.69	$127.70	$127.70
Purchase #7	$78.74	10.339%	$86.8809	$86.88	$86.90	$86.90
7 purchase totals =	$1,010.59		$1,085.1374	$1,085.14	$1,085.15	$1,085.20