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	$163.47	5.865%	$173.0575	$173.06	$173.05	$173.10
Purchase #2	$235.48	6.228%	$250.1457	$250.15	$250.15	$250.10
Purchase #3	$180.98	12.663%	$203.8975	$203.90	$203.90	$203.90
Purchase #4	$68.41	6.376%	$72.7718	$72.77	$72.75	$72.80
Purchase #5	$105.74	6.379%	$112.4852	$112.49	$112.50	$112.50
Purchase #6	$148.28	9.563%	$162.46	$162.46	$162.45	$162.50
Purchase #7	$62.58	12.446%	$70.3687	$70.37	$70.35	$70.40
7 purchase totals =	$964.94		$1,045.1864	$1,045.20	$1,045.15	$1,045.30