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	$114.29	13.850%	$130.1192	$130.12	$130.10	$130.10
Purchase #2	$222.60	12.695%	$250.8591	$250.86	$250.85	$250.90
Purchase #3	$247.49	13.570%	$281.0744	$281.07	$281.05	$281.10
Purchase #4	$119.59	10.811%	$132.5189	$132.52	$132.50	$132.50
Purchase #5	$142.61	3.507%	$147.6113	$147.61	$147.60	$147.60
Purchase #6	$120.76	13.154%	$136.6448	$136.64	$136.65	$136.60
Purchase #7	$162.90	12.624%	$183.4645	$183.46	$183.45	$183.50
7 purchase totals =	$1,130.24		$1,262.2922	$1,262.28	$1,262.20	$1,262.30