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	$226.76	4.525%	$237.0209	$237.02	$237.00	$237.00
Purchase #2	$30.58	3.393%	$31.6176	$31.62	$31.60	$31.60
Purchase #3	$82.27	9.751%	$90.2921	$90.29	$90.30	$90.30
Purchase #4	$93.83	6.539%	$99.9655	$99.97	$99.95	$100.00
Purchase #5	$150.70	13.146%	$170.511	$170.51	$170.50	$170.50
Purchase #6	$180.84	5.214%	$190.269	$190.27	$190.25	$190.30
Purchase #7	$190.79	11.719%	$213.1487	$213.15	$213.15	$213.10
7 purchase totals =	$955.77		$1,032.8248	$1,032.83	$1,032.75	$1,032.80