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	$147.67	4.155%	$153.8057	$153.81	$153.80	$153.80
Purchase #2	$27.38	4.196%	$28.5289	$28.53	$28.55	$28.50
Purchase #3	$41.73	4.385%	$43.5599	$43.56	$43.55	$43.60
Purchase #4	$82.37	5.558%	$86.9481	$86.95	$86.95	$86.90
Purchase #5	$29.35	4.166%	$30.5727	$30.57	$30.55	$30.60
Purchase #6	$217.77	8.385%	$236.03	$236.03	$236.05	$236.00
Purchase #7	$79.81	10.382%	$88.0959	$88.10	$88.10	$88.10
7 purchase totals =	$626.08		$667.5412	$667.55	$667.55	$667.50