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	$148.35	9.442%	$162.3572	$162.36	$162.35	$162.40
Purchase #2	$131.93	12.583%	$148.5308	$148.53	$148.55	$148.50
Purchase #3	$191.81	9.561%	$210.149	$210.15	$210.15	$210.10
Purchase #4	$201.30	10.815%	$223.0706	$223.07	$223.05	$223.10
Purchase #5	$45.82	6.160%	$48.6425	$48.64	$48.65	$48.60
Purchase #6	$80.71	11.555%	$90.036	$90.04	$90.05	$90.00
Purchase #7	$172.28	12.549%	$193.8994	$193.90	$193.90	$193.90
7 purchase totals =	$972.20		$1,076.6855	$1,076.69	$1,076.70	$1,076.60