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	$164.62	6.847%	$175.8915	$175.89	$175.90	$175.90
Purchase #2	$14.48	7.209%	$15.5239	$15.52	$15.50	$15.50
Purchase #3	$160.57	3.382%	$166.0005	$166.00	$166.00	$166.00
Purchase #4	$162.42	5.473%	$171.3092	$171.31	$171.30	$171.30
Purchase #5	$173.38	4.485%	$181.1561	$181.16	$181.15	$181.20
Purchase #6	$148.37	4.571%	$155.152	$155.15	$155.15	$155.20
Purchase #7	$128.79	12.359%	$144.7072	$144.71	$144.70	$144.70
7 purchase totals =	$952.63		$1,009.7404	$1,009.74	$1,009.70	$1,009.80