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	$154.56	3.610%	$160.1396	$160.14	$160.15	$160.10
Purchase #2	$42.88	3.778%	$44.5	$44.50	$44.50	$44.50
Purchase #3	$98.33	10.736%	$108.8867	$108.89	$108.90	$108.90
Purchase #4	$234.37	12.681%	$264.0905	$264.09	$264.10	$264.10
Purchase #5	$172.44	9.638%	$189.0598	$189.06	$189.05	$189.10
Purchase #6	$179.65	4.402%	$187.5582	$187.56	$187.55	$187.60
Purchase #7	$125.29	4.855%	$131.3728	$131.37	$131.35	$131.40
7 purchase totals =	$1,007.52		$1,085.6076	$1,085.61	$1,085.60	$1,085.70