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	$173.25	13.489%	$196.6197	$196.62	$196.60	$196.60
Purchase #2	$39.67	13.114%	$44.8723	$44.87	$44.85	$44.90
Purchase #3	$54.56	4.519%	$57.0256	$57.03	$57.05	$57.00
Purchase #4	$215.72	13.513%	$244.8702	$244.87	$244.85	$244.90
Purchase #5	$94.97	8.396%	$102.9437	$102.94	$102.95	$102.90
Purchase #6	$128.67	8.341%	$139.4024	$139.40	$139.40	$139.40
Purchase #7	$246.67	11.445%	$274.9014	$274.90	$274.90	$274.90
7 purchase totals =	$953.51		$1,060.6353	$1,060.63	$1,060.60	$1,060.60