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	$182.63	4.107%	$190.1306	$190.13	$190.15	$190.10
Purchase #2	$157.49	6.324%	$167.4497	$167.45	$167.45	$167.40
Purchase #3	$70.70	4.504%	$73.8843	$73.88	$73.90	$73.90
Purchase #4	$179.71	10.487%	$198.5562	$198.56	$198.55	$198.60
Purchase #5	$27.66	6.853%	$29.5555	$29.56	$29.55	$29.60
Purchase #6	$245.89	4.167%	$256.1362	$256.14	$256.15	$256.10
Purchase #7	$131.62	8.197%	$142.4089	$142.41	$142.40	$142.40
7 purchase totals =	$995.70		$1,058.1214	$1,058.13	$1,058.15	$1,058.10