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	$58.78	8.562%	$63.8127	$63.81	$63.80	$63.80
Purchase #2	$178.40	12.555%	$200.7981	$200.80	$200.80	$200.80
Purchase #3	$67.75	6.292%	$72.0128	$72.01	$72.00	$72.00
Purchase #4	$212.90	4.408%	$222.2846	$222.28	$222.30	$222.30
Purchase #5	$144.45	7.578%	$155.3964	$155.40	$155.40	$155.40
Purchase #6	$246.55	7.381%	$264.7479	$264.75	$264.75	$264.70
Purchase #7	$40.62	11.259%	$45.1934	$45.19	$45.20	$45.20
7 purchase totals =	$949.45		$1,024.2459	$1,024.24	$1,024.25	$1,024.20