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	$223.46	7.717%	$240.7044	$240.70	$240.70	$240.70
Purchase #2	$195.75	7.541%	$210.5115	$210.51	$210.50	$210.50
Purchase #3	$177.62	10.847%	$196.8864	$196.89	$196.90	$196.90
Purchase #4	$43.33	8.267%	$46.9121	$46.91	$46.90	$46.90
Purchase #5	$71.85	8.692%	$78.0952	$78.10	$78.10	$78.10
Purchase #6	$31.29	10.858%	$34.6875	$34.69	$34.70	$34.70
Purchase #7	$192.74	7.176%	$206.571	$206.57	$206.55	$206.60
7 purchase totals =	$936.04		$1,014.3681	$1,014.37	$1,014.35	$1,014.40