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	$203.32	8.132%	$219.854	$219.85	$219.85	$219.90
Purchase #2	$222.59	10.572%	$246.1222	$246.12	$246.10	$246.10
Purchase #3	$145.49	11.818%	$162.684	$162.68	$162.70	$162.70
Purchase #4	$63.39	12.758%	$71.4773	$71.48	$71.50	$71.50
Purchase #5	$83.87	9.322%	$91.6884	$91.69	$91.70	$91.70
Purchase #6	$93.52	7.623%	$100.649	$100.65	$100.65	$100.60
Purchase #7	$228.72	12.298%	$256.848	$256.85	$256.85	$256.80
7 purchase totals =	$1,040.90		$1,149.3229	$1,149.32	$1,149.35	$1,149.30