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	$90.52	5.322%	$95.3375	$95.34	$95.35	$95.30
Purchase #2	$10.85	6.239%	$11.5269	$11.53	$11.55	$11.50
Purchase #3	$173.41	7.222%	$185.9337	$185.93	$185.95	$185.90
Purchase #4	$208.56	10.362%	$230.171	$230.17	$230.15	$230.20
Purchase #5	$116.81	6.645%	$124.572	$124.57	$124.55	$124.60
Purchase #6	$213.79	4.357%	$223.1048	$223.10	$223.10	$223.10
Purchase #7	$185.82	7.794%	$200.3028	$200.30	$200.30	$200.30
7 purchase totals =	$999.76		$1,070.9487	$1,070.94	$1,070.95	$1,070.90