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	$146.95	3.407%	$151.9566	$151.96	$151.95	$152.00
Purchase #2	$31.34	8.170%	$33.9005	$33.90	$33.90	$33.90
Purchase #3	$238.61	12.549%	$268.5532	$268.55	$268.55	$268.60
Purchase #4	$203.85	9.464%	$223.1424	$223.14	$223.15	$223.10
Purchase #5	$93.47	10.693%	$103.4647	$103.46	$103.45	$103.50
Purchase #6	$95.91	12.841%	$108.2258	$108.23	$108.25	$108.20
Purchase #7	$150.69	6.556%	$160.5692	$160.57	$160.55	$160.60
7 purchase totals =	$960.82		$1,049.8124	$1,049.81	$1,049.80	$1,049.90