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	$76.62	13.253%	$86.7744	$86.77	$86.75	$86.80
Purchase #2	$156.76	3.567%	$162.3516	$162.35	$162.35	$162.40
Purchase #3	$49.78	13.626%	$56.563	$56.56	$56.55	$56.60
Purchase #4	$202.94	5.717%	$214.5421	$214.54	$214.55	$214.50
Purchase #5	$186.61	5.315%	$196.5283	$196.53	$196.55	$196.50
Purchase #6	$206.86	4.370%	$215.8998	$215.90	$215.90	$215.90
Purchase #7	$73.61	10.740%	$81.5157	$81.52	$81.50	$81.50
7 purchase totals =	$953.18		$1,014.1749	$1,014.17	$1,014.15	$1,014.20