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	$246.71	6.185%	$261.969	$261.97	$261.95	$262.00
Purchase #2	$72.45	12.398%	$81.4324	$81.43	$81.45	$81.40
Purchase #3	$54.38	10.134%	$59.8909	$59.89	$59.90	$59.90
Purchase #4	$108.37	7.201%	$116.1737	$116.17	$116.15	$116.20
Purchase #5	$203.85	12.641%	$229.6187	$229.62	$229.60	$229.60
Purchase #6	$158.46	8.171%	$171.4078	$171.41	$171.40	$171.40
Purchase #7	$207.33	13.212%	$234.7224	$234.72	$234.70	$234.70
7 purchase totals =	$1,051.55		$1,155.2149	$1,155.21	$1,155.15	$1,155.20