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	$201.37	4.235%	$209.898	$209.90	$209.90	$209.90
Purchase #2	$66.87	6.789%	$71.4098	$71.41	$71.40	$71.40
Purchase #3	$158.73	7.304%	$170.3236	$170.32	$170.30	$170.30
Purchase #4	$136.50	7.210%	$146.3417	$146.34	$146.35	$146.30
Purchase #5	$142.81	3.720%	$148.1225	$148.12	$148.10	$148.10
Purchase #6	$75.33	3.807%	$78.1978	$78.20	$78.20	$78.20
Purchase #7	$223.92	9.243%	$244.6169	$244.62	$244.60	$244.60
7 purchase totals =	$1,005.53		$1,068.9103	$1,068.91	$1,068.85	$1,068.80