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	$13.29	8.648%	$14.4393	$14.44	$14.45	$14.40
Purchase #2	$75.91	5.404%	$80.0122	$80.01	$80.00	$80.00
Purchase #3	$35.47	4.810%	$37.1761	$37.18	$37.20	$37.20
Purchase #4	$82.27	7.835%	$88.7159	$88.72	$88.70	$88.70
Purchase #5	$55.34	7.647%	$59.5718	$59.57	$59.55	$59.60
Purchase #6	$102.82	7.823%	$110.8636	$110.86	$110.85	$110.90
Purchase #7	$43.73	3.259%	$45.1552	$45.16	$45.15	$45.20
7 purchase totals =	$408.83		$435.9341	$435.94	$435.90	$436.00