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	$129.47	9.368%	$141.5987	$141.60	$141.60	$141.60
Purchase #2	$170.56	12.390%	$191.6924	$191.69	$191.70	$191.70
Purchase #3	$178.73	6.746%	$190.7871	$190.79	$190.80	$190.80
Purchase #4	$221.50	9.665%	$242.908	$242.91	$242.90	$242.90
Purchase #5	$113.69	9.550%	$124.5474	$124.55	$124.55	$124.50
Purchase #6	$49.43	10.499%	$54.6197	$54.62	$54.60	$54.60
Purchase #7	$196.89	4.871%	$206.4805	$206.48	$206.50	$206.50
7 purchase totals =	$1,060.27		$1,152.6338	$1,152.64	$1,152.65	$1,152.60