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	$58.49	5.283%	$61.58	$61.58	$61.60	$61.60
Purchase #2	$213.76	5.303%	$225.0957	$225.10	$225.10	$225.10
Purchase #3	$205.39	4.690%	$215.0228	$215.02	$215.00	$215.00
Purchase #4	$144.28	12.527%	$162.354	$162.35	$162.35	$162.40
Purchase #5	$69.88	12.480%	$78.601	$78.60	$78.60	$78.60
Purchase #6	$80.79	7.506%	$86.8541	$86.85	$86.85	$86.90
Purchase #7	$223.26	11.520%	$248.9796	$248.98	$249.00	$249.00
7 purchase totals =	$995.85		$1,078.4872	$1,078.48	$1,078.50	$1,078.60