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	$176.50	7.474%	$189.6916	$189.69	$189.70	$189.70
Purchase #2	$176.47	11.491%	$196.7482	$196.75	$196.75	$196.70
Purchase #3	$246.52	11.439%	$274.7194	$274.72	$274.70	$274.70
Purchase #4	$104.54	5.538%	$110.3294	$110.33	$110.35	$110.30
Purchase #5	$177.44	10.840%	$196.6745	$196.67	$196.65	$196.70
Purchase #6	$32.86	7.597%	$35.3564	$35.36	$35.35	$35.40
Purchase #7	$27.62	12.617%	$31.1048	$31.10	$31.10	$31.10
7 purchase totals =	$941.95		$1,034.6243	$1,034.62	$1,034.60	$1,034.60