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	$143.47	5.546%	$151.4268	$151.43	$151.45	$151.40
Purchase #2	$32.79	3.435%	$33.9163	$33.92	$33.90	$33.90
Purchase #3	$113.54	13.508%	$128.877	$128.88	$128.90	$128.90
Purchase #4	$88.67	4.328%	$92.5076	$92.51	$92.50	$92.50
Purchase #5	$67.32	12.553%	$75.7707	$75.77	$75.75	$75.80
Purchase #6	$104.99	11.570%	$117.1373	$117.14	$117.15	$117.10
Purchase #7	$148.38	4.414%	$154.9295	$154.93	$154.95	$154.90
7 purchase totals =	$699.16		$754.5652	$754.58	$754.60	$754.50