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	$232.92	8.719%	$253.2283	$253.23	$253.25	$253.20
Purchase #2	$121.25	8.344%	$131.3671	$131.37	$131.35	$131.40
Purchase #3	$119.89	6.442%	$127.6133	$127.61	$127.60	$127.60
Purchase #4	$10.95	8.396%	$11.8694	$11.87	$11.85	$11.90
Purchase #5	$168.80	10.673%	$186.816	$186.82	$186.80	$186.80
Purchase #6	$148.90	11.693%	$166.3109	$166.31	$166.30	$166.30
Purchase #7	$210.54	6.606%	$224.4483	$224.45	$224.45	$224.40
7 purchase totals =	$1,013.25		$1,101.6533	$1,101.66	$1,101.60	$1,101.60