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	$140.41	7.832%	$151.4069	$151.41	$151.40	$151.40
Purchase #2	$181.56	8.286%	$196.6041	$196.60	$196.60	$196.60
Purchase #3	$236.30	7.689%	$254.4691	$254.47	$254.45	$254.50
Purchase #4	$184.93	8.542%	$200.7267	$200.73	$200.75	$200.70
Purchase #5	$79.54	8.108%	$85.9891	$85.99	$86.00	$86.00
Purchase #6	$58.77	11.334%	$65.431	$65.43	$65.45	$65.40
Purchase #7	$43.70	6.223%	$46.4195	$46.42	$46.40	$46.40
7 purchase totals =	$925.21		$1,001.0464	$1,001.05	$1,001.05	$1,001.00