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	$190.44	12.219%	$213.7099	$213.71	$213.70	$213.70
Purchase #2	$198.52	12.224%	$222.7871	$222.79	$222.80	$222.80
Purchase #3	$152.39	3.715%	$158.0513	$158.05	$158.05	$158.10
Purchase #4	$13.93	10.482%	$15.3901	$15.39	$15.40	$15.40
Purchase #5	$166.78	13.608%	$189.4754	$189.48	$189.50	$189.50
Purchase #6	$30.44	6.851%	$32.5254	$32.53	$32.55	$32.50
Purchase #7	$220.93	10.693%	$244.554	$244.55	$244.55	$244.60
7 purchase totals =	$973.43		$1,076.4932	$1,076.50	$1,076.55	$1,076.60