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	$175.74	7.733%	$189.33	$189.33	$189.35	$189.30
Purchase #2	$67.41	4.262%	$70.283	$70.28	$70.30	$70.30
Purchase #3	$174.95	3.123%	$180.4137	$180.41	$180.40	$180.40
Purchase #4	$220.31	6.124%	$233.8018	$233.80	$233.80	$233.80
Purchase #5	$41.25	10.123%	$45.4257	$45.43	$45.45	$45.40
Purchase #6	$200.90	12.298%	$225.6067	$225.61	$225.60	$225.60
Purchase #7	$78.82	10.203%	$86.862	$86.86	$86.85	$86.90
7 purchase totals =	$959.38		$1,031.7229	$1,031.72	$1,031.75	$1,031.70