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	$111.29	11.168%	$123.7189	$123.72	$123.70	$123.70
Purchase #2	$20.64	9.812%	$22.6652	$22.67	$22.65	$22.70
Purchase #3	$132.65	7.186%	$142.1822	$142.18	$142.20	$142.20
Purchase #4	$180.63	3.427%	$186.8202	$186.82	$186.80	$186.80
Purchase #5	$239.98	12.108%	$269.0368	$269.04	$269.05	$269.00
Purchase #6	$178.52	7.204%	$191.3806	$191.38	$191.40	$191.40
Purchase #7	$199.84	5.837%	$211.5047	$211.50	$211.50	$211.50
7 purchase totals =	$1,063.55		$1,147.3086	$1,147.31	$1,147.30	$1,147.30