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	$84.66	12.237%	$95.0198	$95.02	$95.00	$95.00
Purchase #2	$120.51	7.839%	$129.9568	$129.96	$129.95	$130.00
Purchase #3	$228.30	9.777%	$250.6209	$250.62	$250.60	$250.60
Purchase #4	$85.89	7.800%	$92.5894	$92.59	$92.60	$92.60
Purchase #5	$42.54	6.459%	$45.2877	$45.29	$45.30	$45.30
Purchase #6	$173.58	9.826%	$190.636	$190.64	$190.65	$190.60
Purchase #7	$206.59	9.162%	$225.5178	$225.52	$225.50	$225.50
7 purchase totals =	$942.07		$1,029.6284	$1,029.64	$1,029.60	$1,029.60