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	$212.97	4.611%	$222.79	$222.79	$222.80	$222.80
Purchase #2	$145.48	4.798%	$152.4601	$152.46	$152.45	$152.50
Purchase #3	$101.68	10.818%	$112.6797	$112.68	$112.70	$112.70
Purchase #4	$135.89	11.631%	$151.6954	$151.70	$151.70	$151.70
Purchase #5	$205.50	6.864%	$219.6055	$219.61	$219.60	$219.60
Purchase #6	$128.50	6.388%	$136.7086	$136.71	$136.70	$136.70
Purchase #7	$111.49	11.627%	$124.4529	$124.45	$124.45	$124.50
7 purchase totals =	$1,041.51		$1,120.3922	$1,120.40	$1,120.40	$1,120.50