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	$56.32	9.245%	$61.5268	$61.53	$61.55	$61.50
Purchase #2	$174.54	4.556%	$182.492	$182.49	$182.50	$182.50
Purchase #3	$232.75	11.762%	$260.1261	$260.13	$260.15	$260.10
Purchase #4	$189.98	3.408%	$196.4545	$196.45	$196.45	$196.50
Purchase #5	$178.73	9.688%	$196.0454	$196.05	$196.05	$196.00
Purchase #6	$184.69	12.854%	$208.4301	$208.43	$208.45	$208.40
Purchase #7	$17.46	10.216%	$19.2437	$19.24	$19.25	$19.20
7 purchase totals =	$1,034.47		$1,124.3186	$1,124.32	$1,124.40	$1,124.20