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	$195.53	9.380%	$213.8707	$213.87	$213.85	$213.90
Purchase #2	$200.45	11.524%	$223.5499	$223.55	$223.55	$223.50
Purchase #3	$100.37	12.443%	$112.859	$112.86	$112.85	$112.90
Purchase #4	$97.91	12.767%	$110.4102	$110.41	$110.40	$110.40
Purchase #5	$72.53	11.303%	$80.7281	$80.73	$80.75	$80.70
Purchase #6	$207.60	7.650%	$223.4814	$223.48	$223.50	$223.50
Purchase #7	$191.49	9.554%	$209.785	$209.79	$209.80	$209.80
7 purchase totals =	$1,065.88		$1,174.6843	$1,174.69	$1,174.70	$1,174.70