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	$169.31	10.754%	$187.5176	$187.52	$187.50	$187.50
Purchase #2	$177.71	5.566%	$187.6013	$187.60	$187.60	$187.60
Purchase #3	$178.91	3.771%	$185.6567	$185.66	$185.65	$185.70
Purchase #4	$133.57	13.490%	$151.5886	$151.59	$151.60	$151.60
Purchase #5	$235.93	11.429%	$262.8944	$262.89	$262.90	$262.90
Purchase #6	$33.92	6.437%	$36.1034	$36.10	$36.10	$36.10
Purchase #7	$64.47	13.765%	$73.3443	$73.34	$73.35	$73.30
7 purchase totals =	$993.82		$1,084.7063	$1,084.70	$1,084.70	$1,084.70