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	$196.42	8.519%	$213.153	$213.15	$213.15	$213.20
Purchase #2	$229.63	8.259%	$248.5951	$248.60	$248.60	$248.60
Purchase #3	$67.48	4.387%	$70.4403	$70.44	$70.45	$70.40
Purchase #4	$79.56	12.702%	$89.6657	$89.67	$89.65	$89.70
Purchase #5	$160.51	12.507%	$180.585	$180.59	$180.60	$180.60
Purchase #6	$169.46	12.423%	$190.512	$190.51	$190.50	$190.50
Purchase #7	$75.37	4.663%	$78.8845	$78.88	$78.90	$78.90
7 purchase totals =	$978.43		$1,071.8356	$1,071.84	$1,071.85	$1,071.90