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	$239.75	11.144%	$266.4677	$266.47	$266.45	$266.50
Purchase #2	$51.43	4.219%	$53.5998	$53.60	$53.60	$53.60
Purchase #3	$80.29	12.787%	$90.5567	$90.56	$90.55	$90.60
Purchase #4	$250.74	3.708%	$260.0374	$260.04	$260.05	$260.00
Purchase #5	$141.32	12.488%	$158.968	$158.97	$158.95	$159.00
Purchase #6	$82.29	5.530%	$86.8406	$86.84	$86.85	$86.80
Purchase #7	$131.75	4.220%	$137.3099	$137.31	$137.30	$137.30
7 purchase totals =	$977.57		$1,053.7801	$1,053.79	$1,053.75	$1,053.80