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	$95.58	10.343%	$105.4658	$105.47	$105.45	$105.50
Purchase #2	$155.59	4.243%	$162.1917	$162.19	$162.20	$162.20
Purchase #3	$37.77	6.606%	$40.2651	$40.27	$40.25	$40.30
Purchase #4	$130.40	13.348%	$147.8058	$147.81	$147.80	$147.80
Purchase #5	$198.72	6.554%	$211.7441	$211.74	$211.75	$211.70
Purchase #6	$191.85	10.180%	$211.3803	$211.38	$211.40	$211.40
Purchase #7	$196.80	5.411%	$207.4488	$207.45	$207.45	$207.40
7 purchase totals =	$1,006.71		$1,086.3016	$1,086.31	$1,086.30	$1,086.30