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	$231.73	3.760%	$240.443	$240.44	$240.45	$240.40
Purchase #2	$6.90	3.623%	$7.15	$7.15	$7.15	$7.20
Purchase #3	$250.74	5.597%	$264.7739	$264.77	$264.75	$264.80
Purchase #4	$174.37	4.548%	$182.3003	$182.30	$182.30	$182.30
Purchase #5	$225.28	5.667%	$238.0466	$238.05	$238.05	$238.00
Purchase #6	$119.50	3.688%	$123.9072	$123.91	$123.90	$123.90
Purchase #7	$77.72	7.497%	$83.5467	$83.55	$83.55	$83.50
7 purchase totals =	$1,086.24		$1,140.1677	$1,140.17	$1,140.15	$1,140.10