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	$213.29	9.674%	$233.9237	$233.92	$233.90	$233.90
Purchase #2	$195.95	5.201%	$206.1414	$206.14	$206.15	$206.10
Purchase #3	$160.76	12.772%	$181.2923	$181.29	$181.30	$181.30
Purchase #4	$198.33	12.762%	$223.6409	$223.64	$223.65	$223.60
Purchase #5	$233.57	5.258%	$245.8511	$245.85	$245.85	$245.90
Purchase #6	$93.73	10.205%	$103.2951	$103.30	$103.30	$103.30
Purchase #7	$76.64	6.113%	$81.325	$81.33	$81.35	$81.30
7 purchase totals =	$1,172.27		$1,275.4695	$1,275.47	$1,275.50	$1,275.40