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	$120.42	5.717%	$127.3044	$127.30	$127.30	$127.30
Purchase #2	$143.40	5.467%	$151.2397	$151.24	$151.25	$151.20
Purchase #3	$76.51	6.322%	$81.347	$81.35	$81.35	$81.30
Purchase #4	$79.89	8.428%	$86.6231	$86.62	$86.60	$86.60
Purchase #5	$91.54	13.246%	$103.6654	$103.67	$103.65	$103.70
Purchase #6	$200.43	12.432%	$225.3475	$225.35	$225.35	$225.30
Purchase #7	$218.44	8.256%	$236.4744	$236.47	$236.45	$236.50
7 purchase totals =	$930.63		$1,012.0015	$1,012.00	$1,011.95	$1,011.90