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	$163.54	11.555%	$182.437	$182.44	$182.45	$182.40
Purchase #2	$54.28	9.790%	$59.594	$59.59	$59.60	$59.60
Purchase #3	$141.78	7.839%	$152.8941	$152.89	$152.90	$152.90
Purchase #4	$75.45	4.690%	$78.9886	$78.99	$79.00	$79.00
Purchase #5	$208.31	10.832%	$230.8741	$230.87	$230.85	$230.90
Purchase #6	$46.75	4.848%	$49.0164	$49.02	$49.00	$49.00
Purchase #7	$11.74	4.360%	$12.2519	$12.25	$12.25	$12.30
7 purchase totals =	$701.85		$766.0561	$766.05	$766.05	$766.10