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	$196.83	11.162%	$218.8002	$218.80	$218.80	$218.80
Purchase #2	$220.94	8.149%	$238.9444	$238.94	$238.95	$238.90
Purchase #3	$225.89	13.237%	$255.7911	$255.79	$255.80	$255.80
Purchase #4	$191.31	13.235%	$216.6299	$216.63	$216.65	$216.60
Purchase #5	$130.72	11.533%	$145.7959	$145.80	$145.80	$145.80
Purchase #6	$156.90	11.799%	$175.4126	$175.41	$175.40	$175.40
Purchase #7	$182.54	11.839%	$204.1509	$204.15	$204.15	$204.20
7 purchase totals =	$1,305.13		$1,455.5250	$1,455.52	$1,455.55	$1,455.50