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	$196.87	11.446%	$219.4037	$219.40	$219.40	$219.40
Purchase #2	$185.69	13.125%	$210.0618	$210.06	$210.05	$210.10
Purchase #3	$57.37	3.858%	$59.5833	$59.58	$59.60	$59.60
Purchase #4	$133.82	6.256%	$142.1918	$142.19	$142.20	$142.20
Purchase #5	$78.55	3.319%	$81.1571	$81.16	$81.15	$81.20
Purchase #6	$224.78	13.793%	$255.7839	$255.78	$255.80	$255.80
Purchase #7	$80.72	10.682%	$89.3425	$89.34	$89.35	$89.30
7 purchase totals =	$957.80		$1,057.5241	$1,057.51	$1,057.55	$1,057.60