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	$166.32	7.412%	$178.6476	$178.65	$178.65	$178.60
Purchase #2	$26.68	7.137%	$28.5842	$28.58	$28.60	$28.60
Purchase #3	$23.70	3.771%	$24.5937	$24.59	$24.60	$24.60
Purchase #4	$203.34	7.824%	$219.2493	$219.25	$219.25	$219.20
Purchase #5	$85.29	4.756%	$89.3464	$89.35	$89.35	$89.30
Purchase #6	$62.88	13.778%	$71.5436	$71.54	$71.55	$71.50
Purchase #7	$127.53	10.512%	$140.936	$140.94	$140.95	$140.90
7 purchase totals =	$695.74		$752.9008	$752.90	$752.95	$752.70