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	$116.97	11.644%	$130.59	$130.59	$130.60	$130.60
Purchase #2	$54.96	8.526%	$59.6459	$59.65	$59.65	$59.60
Purchase #3	$219.45	6.179%	$233.0098	$233.01	$233.00	$233.00
Purchase #4	$111.53	12.851%	$125.8627	$125.86	$125.85	$125.90
Purchase #5	$166.93	8.157%	$180.5465	$180.55	$180.55	$180.50
Purchase #6	$222.51	11.204%	$247.44	$247.44	$247.45	$247.40
Purchase #7	$66.37	7.731%	$71.5011	$71.50	$71.50	$71.50
7 purchase totals =	$958.72		$1,048.5960	$1,048.60	$1,048.60	$1,048.50