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	$194.98	10.550%	$215.5504	$215.55	$215.55	$215.60
Purchase #2	$196.61	8.575%	$213.4693	$213.47	$213.45	$213.50
Purchase #3	$35.28	3.282%	$36.4379	$36.44	$36.45	$36.40
Purchase #4	$110.44	6.183%	$117.2685	$117.27	$117.25	$117.30
Purchase #5	$150.54	3.418%	$155.6855	$155.69	$155.70	$155.70
Purchase #6	$89.78	6.226%	$95.3697	$95.37	$95.35	$95.40
Purchase #7	$78.72	13.584%	$89.4133	$89.41	$89.40	$89.40
7 purchase totals =	$856.35		$923.1946	$923.20	$923.15	$923.30