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	$124.33	13.768%	$141.4478	$141.45	$141.45	$141.40
Purchase #2	$156.50	5.457%	$165.0402	$165.04	$165.05	$165.00
Purchase #3	$163.55	11.821%	$182.8832	$182.88	$182.90	$182.90
Purchase #4	$216.88	5.865%	$229.6	$229.60	$229.60	$229.60
Purchase #5	$100.69	10.799%	$111.5635	$111.56	$111.55	$111.60
Purchase #6	$214.55	10.479%	$237.0327	$237.03	$237.05	$237.00
Purchase #7	$189.90	12.762%	$214.135	$214.14	$214.15	$214.10
7 purchase totals =	$1,166.40		$1,281.7024	$1,281.70	$1,281.75	$1,281.60