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	$41.44	6.119%	$43.9757	$43.98	$44.00	$44.00
Purchase #2	$82.71	4.698%	$86.5957	$86.60	$86.60	$86.60
Purchase #3	$85.94	5.561%	$90.7191	$90.72	$90.70	$90.70
Purchase #4	$52.80	12.461%	$59.3794	$59.38	$59.40	$59.40
Purchase #5	$25.90	13.710%	$29.4509	$29.45	$29.45	$29.50
Purchase #6	$117.76	6.771%	$125.7335	$125.73	$125.75	$125.70
Purchase #7	$25.84	3.150%	$26.654	$26.65	$26.65	$26.70
7 purchase totals =	$432.39		$462.5083	$462.51	$462.55	$462.60