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	$209.42	4.809%	$219.491	$219.49	$219.50	$219.50
Purchase #2	$52.43	6.458%	$55.8159	$55.82	$55.80	$55.80
Purchase #3	$70.57	3.134%	$72.7817	$72.78	$72.80	$72.80
Purchase #4	$218.29	4.768%	$228.6981	$228.70	$228.70	$228.70
Purchase #5	$45.60	4.217%	$47.523	$47.52	$47.50	$47.50
Purchase #6	$226.44	4.800%	$237.3091	$237.31	$237.30	$237.30
Purchase #7	$184.56	4.809%	$193.4355	$193.44	$193.45	$193.40
7 purchase totals =	$1,007.31		$1,055.0543	$1,055.06	$1,055.05	$1,055.00