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	$234.51	11.136%	$260.625	$260.63	$260.65	$260.60
Purchase #2	$210.37	9.853%	$231.0978	$231.10	$231.10	$231.10
Purchase #3	$66.45	9.134%	$72.5195	$72.52	$72.50	$72.50
Purchase #4	$59.27	5.241%	$62.3763	$62.38	$62.40	$62.40
Purchase #5	$195.31	8.242%	$211.4075	$211.41	$211.40	$211.40
Purchase #6	$79.38	8.290%	$85.9606	$85.96	$85.95	$86.00
Purchase #7	$117.82	7.860%	$127.0807	$127.08	$127.10	$127.10
7 purchase totals =	$963.11		$1,051.0674	$1,051.08	$1,051.10	$1,051.10