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	$114.50	4.303%	$119.4269	$119.43	$119.45	$119.40
Purchase #2	$188.96	11.502%	$210.6942	$210.69	$210.70	$210.70
Purchase #3	$189.67	3.811%	$196.8983	$196.90	$196.90	$196.90
Purchase #4	$218.74	13.361%	$247.9659	$247.97	$247.95	$248.00
Purchase #5	$49.58	11.867%	$55.4637	$55.46	$55.45	$55.50
Purchase #6	$171.37	10.255%	$188.944	$188.94	$188.95	$188.90
Purchase #7	$18.70	4.382%	$19.5194	$19.52	$19.50	$19.50
7 purchase totals =	$951.52		$1,038.9124	$1,038.91	$1,038.90	$1,038.90