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	$187.35	4.209%	$195.2356	$195.24	$195.25	$195.20
Purchase #2	$206.69	9.780%	$226.9043	$226.90	$226.90	$226.90
Purchase #3	$113.59	9.732%	$124.6446	$124.64	$124.65	$124.60
Purchase #4	$114.44	7.779%	$123.3423	$123.34	$123.35	$123.30
Purchase #5	$220.89	9.336%	$241.5123	$241.51	$241.50	$241.50
Purchase #6	$128.75	10.390%	$142.1271	$142.13	$142.15	$142.10
Purchase #7	$48.84	6.601%	$52.0639	$52.06	$52.05	$52.10
7 purchase totals =	$1,020.55		$1,105.8301	$1,105.82	$1,105.85	$1,105.70