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	$198.33	3.656%	$205.5809	$205.58	$205.60	$205.60
Purchase #2	$5.38	10.120%	$5.9245	$5.92	$5.90	$5.90
Purchase #3	$196.50	13.424%	$222.8782	$222.88	$222.90	$222.90
Purchase #4	$61.89	11.820%	$69.2054	$69.21	$69.20	$69.20
Purchase #5	$221.66	7.768%	$238.8785	$238.88	$238.90	$238.90
Purchase #6	$123.33	11.451%	$137.4525	$137.45	$137.45	$137.50
Purchase #7	$226.50	8.129%	$244.9122	$244.91	$244.90	$244.90
7 purchase totals =	$1,033.59		$1,124.8322	$1,124.83	$1,124.85	$1,124.90