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	$222.79	11.658%	$248.7629	$248.76	$248.75	$248.80
Purchase #2	$215.37	8.438%	$233.5429	$233.54	$233.55	$233.50
Purchase #3	$83.60	9.391%	$91.4509	$91.45	$91.45	$91.50
Purchase #4	$185.25	4.834%	$194.205	$194.21	$194.20	$194.20
Purchase #5	$89.93	5.778%	$95.1262	$95.13	$95.15	$95.10
Purchase #6	$91.47	5.231%	$96.2548	$96.25	$96.25	$96.30
Purchase #7	$77.51	10.853%	$85.9222	$85.92	$85.90	$85.90
7 purchase totals =	$965.92		$1,045.2649	$1,045.26	$1,045.25	$1,045.30