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	$182.85	4.131%	$190.4035	$190.40	$190.40	$190.40
Purchase #2	$23.31	12.863%	$26.3084	$26.31	$26.30	$26.30
Purchase #3	$193.33	10.584%	$213.792	$213.79	$213.80	$213.80
Purchase #4	$38.47	12.497%	$43.2776	$43.28	$43.30	$43.30
Purchase #5	$196.64	10.119%	$216.538	$216.54	$216.55	$216.50
Purchase #6	$58.97	12.837%	$66.54	$66.54	$66.55	$66.50
Purchase #7	$230.87	9.757%	$253.396	$253.40	$253.40	$253.40
7 purchase totals =	$924.44		$1,010.2555	$1,010.26	$1,010.30	$1,010.20