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	$174.86	13.815%	$199.0169	$199.02	$199.00	$199.00
Purchase #2	$62.45	13.850%	$71.0993	$71.10	$71.10	$71.10
Purchase #3	$193.40	13.550%	$219.6057	$219.61	$219.60	$219.60
Purchase #4	$145.69	13.112%	$164.7929	$164.79	$164.80	$164.80
Purchase #5	$59.67	12.134%	$66.9104	$66.91	$66.90	$66.90
Purchase #6	$176.75	12.778%	$199.3351	$199.34	$199.35	$199.30
Purchase #7	$130.40	9.485%	$142.7684	$142.77	$142.75	$142.80
7 purchase totals =	$943.22		$1,063.5287	$1,063.54	$1,063.50	$1,063.50