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	$31.45	7.134%	$33.6936	$33.69	$33.70	$33.70
Purchase #2	$180.60	7.627%	$194.3744	$194.37	$194.35	$194.40
Purchase #3	$158.91	7.550%	$170.9077	$170.91	$170.90	$170.90
Purchase #4	$59.51	11.121%	$66.1281	$66.13	$66.15	$66.10
Purchase #5	$174.78	12.361%	$196.3846	$196.38	$196.40	$196.40
Purchase #6	$172.82	10.169%	$190.3941	$190.39	$190.40	$190.40
Purchase #7	$88.76	9.251%	$96.9712	$96.97	$96.95	$97.00
7 purchase totals =	$866.83		$948.8537	$948.84	$948.85	$948.90