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	$185.35	8.155%	$200.4653	$200.47	$200.45	$200.50
Purchase #2	$20.62	12.453%	$23.1878	$23.19	$23.20	$23.20
Purchase #3	$84.56	6.345%	$89.9253	$89.93	$89.95	$89.90
Purchase #4	$72.88	3.607%	$75.5088	$75.51	$75.50	$75.50
Purchase #5	$170.34	4.678%	$178.3085	$178.31	$178.30	$178.30
Purchase #6	$229.46	9.326%	$250.8594	$250.86	$250.85	$250.90
Purchase #7	$189.32	6.406%	$201.4478	$201.45	$201.45	$201.40
7 purchase totals =	$952.53		$1,019.7029	$1,019.72	$1,019.70	$1,019.70