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	$125.82	13.625%	$142.963	$142.96	$142.95	$143.00
Purchase #2	$125.62	3.220%	$129.665	$129.67	$129.65	$129.70
Purchase #3	$222.52	3.121%	$229.4648	$229.46	$229.45	$229.50
Purchase #4	$180.65	8.837%	$196.614	$196.61	$196.60	$196.60
Purchase #5	$110.59	11.260%	$123.0424	$123.04	$123.05	$123.00
Purchase #6	$106.29	10.704%	$117.6673	$117.67	$117.65	$117.70
Purchase #7	$100.95	8.297%	$109.3258	$109.33	$109.35	$109.30
7 purchase totals =	$972.44		$1,048.7423	$1,048.74	$1,048.70	$1,048.80