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	$104.44	7.320%	$112.085	$112.09	$112.10	$112.10
Purchase #2	$77.27	7.608%	$83.1487	$83.15	$83.15	$83.10
Purchase #3	$114.87	13.658%	$130.5589	$130.56	$130.55	$130.60
Purchase #4	$57.33	8.162%	$62.0093	$62.01	$62.00	$62.00
Purchase #5	$174.34	8.478%	$189.1205	$189.12	$189.10	$189.10
Purchase #6	$198.97	4.794%	$208.5086	$208.51	$208.50	$208.50
Purchase #7	$246.49	13.194%	$279.0119	$279.01	$279.00	$279.00
7 purchase totals =	$973.71		$1,064.4429	$1,064.45	$1,064.40	$1,064.40