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	$127.49	10.705%	$141.1378	$141.14	$141.15	$141.10
Purchase #2	$125.76	4.758%	$131.7437	$131.74	$131.75	$131.70
Purchase #3	$213.75	3.676%	$221.6075	$221.61	$221.60	$221.60
Purchase #4	$217.47	5.564%	$229.57	$229.57	$229.55	$229.60
Purchase #5	$94.32	13.358%	$106.9193	$106.92	$106.90	$106.90
Purchase #6	$55.33	12.507%	$62.2501	$62.25	$62.25	$62.30
Purchase #7	$162.40	3.862%	$168.6719	$168.67	$168.65	$168.70
7 purchase totals =	$996.52		$1,061.9003	$1,061.90	$1,061.85	$1,061.90