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	$191.57	4.494%	$200.1792	$200.18	$200.20	$200.20
Purchase #2	$249.70	12.778%	$281.6067	$281.61	$281.60	$281.60
Purchase #3	$99.52	12.282%	$111.743	$111.74	$111.75	$111.70
Purchase #4	$241.31	7.550%	$259.5289	$259.53	$259.55	$259.50
Purchase #5	$52.85	13.202%	$59.8273	$59.83	$59.85	$59.80
Purchase #6	$201.58	8.417%	$218.547	$218.55	$218.55	$218.50
Purchase #7	$95.54	7.563%	$102.7657	$102.77	$102.75	$102.80
7 purchase totals =	$1,132.07		$1,234.1978	$1,234.21	$1,234.25	$1,234.10