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	$219.30	11.753%	$245.0743	$245.07	$245.05	$245.10
Purchase #2	$54.53	9.144%	$59.5162	$59.52	$59.50	$59.50
Purchase #3	$105.63	7.697%	$113.7603	$113.76	$113.75	$113.80
Purchase #4	$136.58	3.731%	$141.6758	$141.68	$141.70	$141.70
Purchase #5	$131.51	12.530%	$147.9882	$147.99	$148.00	$148.00
Purchase #6	$241.48	5.439%	$254.6141	$254.61	$254.60	$254.60
Purchase #7	$137.48	8.226%	$148.7891	$148.79	$148.80	$148.80
7 purchase totals =	$1,026.51		$1,111.4180	$1,111.42	$1,111.40	$1,111.50