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	$69.70	4.655%	$72.9445	$72.94	$72.95	$72.90
Purchase #2	$13.83	3.551%	$14.3211	$14.32	$14.30	$14.30
Purchase #3	$143.81	10.129%	$158.3765	$158.38	$158.40	$158.40
Purchase #4	$121.69	7.117%	$130.3507	$130.35	$130.35	$130.40
Purchase #5	$205.74	6.189%	$218.4732	$218.47	$218.45	$218.50
Purchase #6	$160.49	7.468%	$172.4754	$172.48	$172.50	$172.50
Purchase #7	$140.90	11.406%	$156.9711	$156.97	$156.95	$157.00
7 purchase totals =	$856.16		$923.9125	$923.91	$923.90	$924.00