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	$190.55	5.460%	$200.954	$200.95	$200.95	$201.00
Purchase #2	$119.91	11.388%	$133.5654	$133.57	$133.55	$133.60
Purchase #3	$173.31	9.555%	$189.8698	$189.87	$189.85	$189.90
Purchase #4	$52.87	12.192%	$59.3159	$59.32	$59.30	$59.30
Purchase #5	$125.56	10.624%	$138.8995	$138.90	$138.90	$138.90
Purchase #6	$232.31	13.840%	$264.4617	$264.46	$264.45	$264.50
Purchase #7	$35.93	6.873%	$38.3995	$38.40	$38.40	$38.40
7 purchase totals =	$930.44		$1,025.4658	$1,025.47	$1,025.40	$1,025.60