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	$211.46	12.553%	$238.0046	$238.00	$238.00	$238.00
Purchase #2	$33.85	7.777%	$36.4825	$36.48	$36.50	$36.50
Purchase #3	$160.35	5.705%	$169.498	$169.50	$169.50	$169.50
Purchase #4	$223.34	8.292%	$241.8594	$241.86	$241.85	$241.90
Purchase #5	$245.53	3.244%	$253.495	$253.50	$253.50	$253.50
Purchase #6	$165.57	5.864%	$175.279	$175.28	$175.30	$175.30
Purchase #7	$146.30	4.511%	$152.8996	$152.90	$152.90	$152.90
7 purchase totals =	$1,186.40		$1,267.5181	$1,267.52	$1,267.55	$1,267.60