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	$172.36	5.557%	$181.938	$181.94	$181.95	$181.90
Purchase #2	$165.52	3.314%	$171.0053	$171.01	$171.00	$171.00
Purchase #3	$75.87	8.599%	$82.3941	$82.39	$82.40	$82.40
Purchase #4	$137.25	4.552%	$143.4976	$143.50	$143.50	$143.50
Purchase #5	$55.92	3.243%	$57.7335	$57.73	$57.75	$57.70
Purchase #6	$146.59	12.611%	$165.0765	$165.08	$165.10	$165.10
Purchase #7	$203.70	9.673%	$223.4039	$223.40	$223.40	$223.40
7 purchase totals =	$957.21		$1,025.0489	$1,025.05	$1,025.10	$1,025.00