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	$59.59	4.167%	$62.0731	$62.07	$62.05	$62.10
Purchase #2	$111.90	10.270%	$123.3921	$123.39	$123.40	$123.40
Purchase #3	$72.52	8.733%	$78.8532	$78.85	$78.85	$78.90
Purchase #4	$11.96	11.199%	$13.2994	$13.30	$13.30	$13.30
Purchase #5	$194.97	12.614%	$219.5635	$219.56	$219.55	$219.60
Purchase #6	$165.73	6.304%	$176.1776	$176.18	$176.20	$176.20
Purchase #7	$208.44	13.734%	$237.0671	$237.07	$237.05	$237.10
7 purchase totals =	$825.11		$910.4260	$910.42	$910.40	$910.60