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	$242.42	9.481%	$265.4038	$265.40	$265.40	$265.40
Purchase #2	$234.93	6.586%	$250.4025	$250.40	$250.40	$250.40
Purchase #3	$110.25	3.764%	$114.3998	$114.40	$114.40	$114.40
Purchase #4	$240.53	9.419%	$263.1855	$263.19	$263.20	$263.20
Purchase #5	$38.87	12.340%	$43.6666	$43.67	$43.65	$43.70
Purchase #6	$154.95	6.174%	$164.5166	$164.52	$164.50	$164.50
Purchase #7	$95.52	3.147%	$98.526	$98.53	$98.55	$98.50
7 purchase totals =	$1,117.47		$1,200.1008	$1,200.11	$1,200.10	$1,200.10