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	$42.72	3.577%	$44.2481	$44.25	$44.25	$44.20
Purchase #2	$111.45	6.273%	$118.4413	$118.44	$118.45	$118.40
Purchase #3	$178.73	6.588%	$190.5047	$190.50	$190.50	$190.50
Purchase #4	$96.51	6.832%	$103.1036	$103.10	$103.10	$103.10
Purchase #5	$97.78	3.537%	$101.2385	$101.24	$101.25	$101.20
Purchase #6	$207.28	7.326%	$222.4653	$222.47	$222.45	$222.50
Purchase #7	$218.40	8.152%	$236.204	$236.20	$236.20	$236.20
7 purchase totals =	$952.87		$1,016.2055	$1,016.20	$1,016.20	$1,016.10