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	$147.48	8.175%	$159.5365	$159.54	$159.55	$159.50
Purchase #2	$147.72	6.298%	$157.0234	$157.02	$157.00	$157.00
Purchase #3	$189.36	3.794%	$196.5443	$196.54	$196.55	$196.50
Purchase #4	$115.85	4.467%	$121.025	$121.03	$121.05	$121.00
Purchase #5	$154.64	13.160%	$174.9906	$174.99	$175.00	$175.00
Purchase #6	$36.87	11.141%	$40.9777	$40.98	$41.00	$41.00
Purchase #7	$161.33	3.113%	$166.3522	$166.35	$166.35	$166.40
7 purchase totals =	$953.25		$1,016.4497	$1,016.45	$1,016.50	$1,016.40