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	$196.48	4.663%	$205.6419	$205.64	$205.65	$205.60
Purchase #2	$19.83	7.715%	$21.3599	$21.36	$21.35	$21.40
Purchase #3	$143.52	10.337%	$158.3557	$158.36	$158.35	$158.40
Purchase #4	$245.27	11.814%	$274.2462	$274.25	$274.25	$274.20
Purchase #5	$44.80	5.717%	$47.3612	$47.36	$47.35	$47.40
Purchase #6	$223.46	4.531%	$233.585	$233.59	$233.60	$233.60
Purchase #7	$218.43	9.867%	$239.9825	$239.98	$240.00	$240.00
7 purchase totals =	$1,091.79		$1,180.5324	$1,180.54	$1,180.55	$1,180.60