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	$159.81	9.800%	$175.4714	$175.47	$175.45	$175.50
Purchase #2	$187.88	9.696%	$206.0968	$206.10	$206.10	$206.10
Purchase #3	$211.50	5.546%	$223.2298	$223.23	$223.25	$223.20
Purchase #4	$53.76	4.183%	$56.0088	$56.01	$56.00	$56.00
Purchase #5	$146.27	7.231%	$156.8468	$156.85	$156.85	$156.80
Purchase #6	$167.74	8.183%	$181.4662	$181.47	$181.45	$181.50
Purchase #7	$72.80	7.665%	$78.3801	$78.38	$78.40	$78.40
7 purchase totals =	$999.76		$1,077.4999	$1,077.51	$1,077.50	$1,077.50