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	$169.27	3.591%	$175.3485	$175.35	$175.35	$175.30
Purchase #2	$215.94	6.149%	$229.2182	$229.22	$229.20	$229.20
Purchase #3	$174.78	3.793%	$181.4094	$181.41	$181.40	$181.40
Purchase #4	$95.67	5.414%	$100.8496	$100.85	$100.85	$100.80
Purchase #5	$127.31	3.263%	$131.4641	$131.46	$131.45	$131.50
Purchase #6	$115.33	11.344%	$128.413	$128.41	$128.40	$128.40
Purchase #7	$217.27	6.439%	$231.26	$231.26	$231.25	$231.30
7 purchase totals =	$1,115.57		$1,177.9628	$1,177.96	$1,177.90	$1,177.90