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	$164.26	5.654%	$173.5473	$173.55	$173.55	$173.50
Purchase #2	$113.56	9.591%	$124.4515	$124.45	$124.45	$124.50
Purchase #3	$160.79	5.667%	$169.902	$169.90	$169.90	$169.90
Purchase #4	$151.33	12.118%	$169.6682	$169.67	$169.65	$169.70
Purchase #5	$214.71	9.193%	$234.4483	$234.45	$234.45	$234.40
Purchase #6	$129.54	13.823%	$147.4463	$147.45	$147.45	$147.40
Purchase #7	$138.71	4.872%	$145.468	$145.47	$145.45	$145.50
7 purchase totals =	$1,072.90		$1,164.9316	$1,164.94	$1,164.90	$1,164.90