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	$238.71	10.188%	$263.0298	$263.03	$263.05	$263.00
Purchase #2	$52.95	9.291%	$57.8696	$57.87	$57.85	$57.90
Purchase #3	$234.86	6.267%	$249.5787	$249.58	$249.60	$249.60
Purchase #4	$7.73	7.125%	$8.2808	$8.28	$8.30	$8.30
Purchase #5	$83.47	3.443%	$86.3439	$86.34	$86.35	$86.30
Purchase #6	$215.46	3.164%	$222.2772	$222.28	$222.30	$222.30
Purchase #7	$110.47	11.678%	$123.3707	$123.37	$123.35	$123.40
7 purchase totals =	$943.65		$1,010.7507	$1,010.75	$1,010.80	$1,010.80