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	$169.81	8.424%	$184.1148	$184.11	$184.10	$184.10
Purchase #2	$95.45	5.488%	$100.6883	$100.69	$100.70	$100.70
Purchase #3	$87.31	5.257%	$91.8999	$91.90	$91.90	$91.90
Purchase #4	$53.88	10.628%	$59.6064	$59.61	$59.60	$59.60
Purchase #5	$185.99	5.752%	$196.6881	$196.69	$196.70	$196.70
Purchase #6	$131.95	13.310%	$149.5125	$149.51	$149.50	$149.50
Purchase #7	$241.55	9.309%	$264.0359	$264.04	$264.05	$264.00
7 purchase totals =	$965.94		$1,046.5459	$1,046.55	$1,046.55	$1,046.50