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	$32.71	4.858%	$34.2991	$34.30	$34.30	$34.30
Purchase #2	$192.90	12.365%	$216.7521	$216.75	$216.75	$216.80
Purchase #3	$245.25	4.765%	$256.9362	$256.94	$256.95	$256.90
Purchase #4	$97.75	3.608%	$101.2768	$101.28	$101.30	$101.30
Purchase #5	$25.80	8.320%	$27.9466	$27.95	$27.95	$27.90
Purchase #6	$72.73	7.266%	$78.0146	$78.01	$78.00	$78.00
Purchase #7	$11.56	6.502%	$12.3116	$12.31	$12.30	$12.30
7 purchase totals =	$678.70		$727.5370	$727.54	$727.55	$727.50