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	$85.82	9.846%	$94.2698	$94.27	$94.25	$94.30
Purchase #2	$36.56	4.687%	$38.2736	$38.27	$38.25	$38.30
Purchase #3	$142.36	11.160%	$158.2474	$158.25	$158.25	$158.20
Purchase #4	$204.65	5.204%	$215.3	$215.30	$215.30	$215.30
Purchase #5	$185.59	9.445%	$203.119	$203.12	$203.10	$203.10
Purchase #6	$233.37	11.673%	$260.6113	$260.61	$260.60	$260.60
Purchase #7	$63.57	3.112%	$65.5483	$65.55	$65.55	$65.50
7 purchase totals =	$951.92		$1,035.3694	$1,035.37	$1,035.30	$1,035.30