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	$41.32	10.636%	$45.7148	$45.71	$45.70	$45.70
Purchase #2	$154.35	5.547%	$162.9118	$162.91	$162.90	$162.90
Purchase #3	$45.86	4.394%	$47.8751	$47.88	$47.90	$47.90
Purchase #4	$129.36	8.304%	$140.1021	$140.10	$140.10	$140.10
Purchase #5	$164.76	5.457%	$173.751	$173.75	$173.75	$173.80
Purchase #6	$76.37	6.614%	$81.4211	$81.42	$81.40	$81.40
Purchase #7	$213.43	4.749%	$223.5658	$223.57	$223.55	$223.60
7 purchase totals =	$825.45		$875.3417	$875.34	$875.30	$875.40