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	$209.26	6.452%	$222.7615	$222.76	$222.75	$222.80
Purchase #2	$86.49	10.473%	$95.5481	$95.55	$95.55	$95.50
Purchase #3	$88.53	11.761%	$98.942	$98.94	$98.95	$98.90
Purchase #4	$93.49	13.153%	$105.7867	$105.79	$105.80	$105.80
Purchase #5	$184.92	8.241%	$200.1593	$200.16	$200.15	$200.20
Purchase #6	$194.48	8.326%	$210.6724	$210.67	$210.65	$210.70
Purchase #7	$73.53	13.638%	$83.558	$83.56	$83.55	$83.60
7 purchase totals =	$930.70		$1,017.4280	$1,017.43	$1,017.40	$1,017.50