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	$175.75	8.126%	$190.0314	$190.03	$190.05	$190.00
Purchase #2	$119.98	9.379%	$131.2329	$131.23	$131.25	$131.20
Purchase #3	$98.67	6.804%	$105.3835	$105.38	$105.40	$105.40
Purchase #4	$52.47	8.562%	$56.9625	$56.96	$56.95	$57.00
Purchase #5	$94.38	7.199%	$101.1744	$101.17	$101.15	$101.20
Purchase #6	$214.27	7.836%	$231.0602	$231.06	$231.05	$231.10
Purchase #7	$225.84	3.200%	$233.0669	$233.07	$233.05	$233.10
7 purchase totals =	$981.36		$1,048.9118	$1,048.90	$1,048.90	$1,049.00