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	$214.76	13.499%	$243.7505	$243.75	$243.75	$243.80
Purchase #2	$126.80	3.168%	$130.817	$130.82	$130.80	$130.80
Purchase #3	$101.98	7.392%	$109.5184	$109.52	$109.50	$109.50
Purchase #4	$191.27	4.427%	$199.7375	$199.74	$199.75	$199.70
Purchase #5	$164.78	6.700%	$175.8203	$175.82	$175.80	$175.80
Purchase #6	$9.92	13.451%	$11.2543	$11.25	$11.25	$11.30
Purchase #7	$126.41	3.639%	$131.0101	$131.01	$131.00	$131.00
7 purchase totals =	$935.92		$1,001.9081	$1,001.91	$1,001.85	$1,001.90