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	$101.61	9.546%	$111.3097	$111.31	$111.30	$111.30
Purchase #2	$11.43	10.537%	$12.6344	$12.63	$12.65	$12.60
Purchase #3	$246.30	12.507%	$277.1047	$277.10	$277.10	$277.10
Purchase #4	$249.84	12.370%	$280.7452	$280.75	$280.75	$280.70
Purchase #5	$109.88	12.579%	$123.7018	$123.70	$123.70	$123.70
Purchase #6	$111.56	4.303%	$116.3604	$116.36	$116.35	$116.40
Purchase #7	$143.48	6.210%	$152.3901	$152.39	$152.40	$152.40
7 purchase totals =	$974.10		$1,074.2463	$1,074.24	$1,074.25	$1,074.20