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	$177.44	10.688%	$196.4048	$196.40	$196.40	$196.40
Purchase #2	$75.90	6.785%	$81.0498	$81.05	$81.05	$81.00
Purchase #3	$234.76	4.343%	$244.9556	$244.96	$244.95	$245.00
Purchase #4	$226.69	6.116%	$240.5544	$240.55	$240.55	$240.60
Purchase #5	$89.52	3.169%	$92.3569	$92.36	$92.35	$92.40
Purchase #6	$177.70	3.836%	$184.5166	$184.52	$184.50	$184.50
Purchase #7	$98.81	13.129%	$111.7828	$111.78	$111.80	$111.80
7 purchase totals =	$1,080.82		$1,151.6209	$1,151.62	$1,151.60	$1,151.70