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	$96.31	8.801%	$104.7862	$104.79	$104.80	$104.80
Purchase #2	$27.71	8.870%	$30.1679	$30.17	$30.15	$30.20
Purchase #3	$95.81	7.541%	$103.035	$103.04	$103.05	$103.00
Purchase #4	$143.99	9.325%	$157.4171	$157.42	$157.40	$157.40
Purchase #5	$168.98	12.817%	$190.6382	$190.64	$190.65	$190.60
Purchase #6	$223.55	8.493%	$242.5361	$242.54	$242.55	$242.50
Purchase #7	$170.30	11.817%	$190.4244	$190.42	$190.40	$190.40
7 purchase totals =	$926.65		$1,019.0049	$1,019.02	$1,019.00	$1,018.90