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	$141.89	6.147%	$150.612	$150.61	$150.60	$150.60
Purchase #2	$191.29	10.668%	$211.6968	$211.70	$211.70	$211.70
Purchase #3	$56.90	10.526%	$62.8893	$62.89	$62.90	$62.90
Purchase #4	$198.61	7.680%	$213.8632	$213.86	$213.85	$213.90
Purchase #5	$100.97	7.314%	$108.3549	$108.35	$108.35	$108.40
Purchase #6	$233.96	12.823%	$263.9607	$263.96	$263.95	$264.00
Purchase #7	$233.77	8.597%	$253.8672	$253.87	$253.85	$253.90
7 purchase totals =	$1,157.39		$1,265.2441	$1,265.24	$1,265.20	$1,265.40