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	$71.60	7.579%	$77.0266	$77.03	$77.05	$77.00
Purchase #2	$246.43	7.122%	$263.9807	$263.98	$264.00	$264.00
Purchase #3	$172.56	10.619%	$190.8841	$190.88	$190.90	$190.90
Purchase #4	$66.43	6.359%	$70.6543	$70.65	$70.65	$70.70
Purchase #5	$226.95	12.460%	$255.228	$255.23	$255.25	$255.20
Purchase #6	$50.26	5.779%	$53.1645	$53.16	$53.15	$53.20
Purchase #7	$177.99	3.712%	$184.597	$184.60	$184.60	$184.60
7 purchase totals =	$1,012.22		$1,095.5352	$1,095.53	$1,095.60	$1,095.60