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	$95.54	9.802%	$104.9048	$104.90	$104.90	$104.90
Purchase #2	$72.37	10.468%	$79.9457	$79.95	$79.95	$79.90
Purchase #3	$26.71	6.499%	$28.4459	$28.45	$28.45	$28.40
Purchase #4	$217.90	13.708%	$247.7697	$247.77	$247.75	$247.80
Purchase #5	$130.88	6.270%	$139.0862	$139.09	$139.10	$139.10
Purchase #6	$233.65	5.502%	$246.5054	$246.51	$246.50	$246.50
Purchase #7	$191.48	12.166%	$214.7755	$214.78	$214.80	$214.80
7 purchase totals =	$968.53		$1,061.4332	$1,061.45	$1,061.45	$1,061.40