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	$150.92	4.423%	$157.5952	$157.60	$157.60	$157.60
Purchase #2	$150.35	4.142%	$156.5775	$156.58	$156.60	$156.60
Purchase #3	$155.87	7.874%	$168.1432	$168.14	$168.15	$168.10
Purchase #4	$173.52	13.502%	$196.9487	$196.95	$196.95	$196.90
Purchase #5	$12.89	7.358%	$13.8384	$13.84	$13.85	$13.80
Purchase #6	$152.73	11.662%	$170.5414	$170.54	$170.55	$170.50
Purchase #7	$153.45	12.434%	$172.53	$172.53	$172.55	$172.50
7 purchase totals =	$949.73		$1,036.1744	$1,036.18	$1,036.25	$1,036.00