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	$182.86	10.112%	$201.3508	$201.35	$201.35	$201.40
Purchase #2	$116.94	9.823%	$128.427	$128.43	$128.45	$128.40
Purchase #3	$51.73	3.845%	$53.719	$53.72	$53.70	$53.70
Purchase #4	$234.82	5.724%	$248.2611	$248.26	$248.25	$248.30
Purchase #5	$182.80	9.580%	$200.3122	$200.31	$200.30	$200.30
Purchase #6	$113.63	8.784%	$123.6113	$123.61	$123.60	$123.60
Purchase #7	$179.45	11.223%	$199.5897	$199.59	$199.60	$199.60
7 purchase totals =	$1,062.23		$1,155.2711	$1,155.27	$1,155.25	$1,155.30