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	$147.47	6.505%	$157.0629	$157.06	$157.05	$157.10
Purchase #2	$18.61	10.763%	$20.613	$20.61	$20.60	$20.60
Purchase #3	$223.85	8.547%	$242.9825	$242.98	$243.00	$243.00
Purchase #4	$248.48	6.354%	$264.2684	$264.27	$264.25	$264.30
Purchase #5	$203.84	3.277%	$210.5198	$210.52	$210.50	$210.50
Purchase #6	$9.63	10.398%	$10.6313	$10.63	$10.65	$10.60
Purchase #7	$140.83	12.801%	$158.8576	$158.86	$158.85	$158.90
7 purchase totals =	$992.71		$1,064.9355	$1,064.93	$1,064.90	$1,065.00