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	$204.59	4.348%	$213.4856	$213.49	$213.50	$213.50
Purchase #2	$114.95	4.339%	$119.9377	$119.94	$119.95	$119.90
Purchase #3	$237.89	4.651%	$248.9543	$248.95	$248.95	$249.00
Purchase #4	$85.57	11.351%	$95.2831	$95.28	$95.30	$95.30
Purchase #5	$206.60	13.472%	$234.4332	$234.43	$234.45	$234.40
Purchase #6	$110.87	8.754%	$120.5756	$120.58	$120.60	$120.60
Purchase #7	$74.80	5.154%	$78.6552	$78.66	$78.65	$78.70
7 purchase totals =	$1,035.27		$1,111.3247	$1,111.33	$1,111.40	$1,111.40