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	$85.71	10.544%	$94.7473	$94.75	$94.75	$94.70
Purchase #2	$131.61	4.753%	$137.8654	$137.87	$137.85	$137.90
Purchase #3	$199.34	4.651%	$208.6113	$208.61	$208.60	$208.60
Purchase #4	$93.91	12.857%	$105.984	$105.98	$106.00	$106.00
Purchase #5	$110.75	6.292%	$117.7184	$117.72	$117.70	$117.70
Purchase #6	$86.27	4.165%	$89.8631	$89.86	$89.85	$89.90
Purchase #7	$246.88	7.276%	$264.843	$264.84	$264.85	$264.80
7 purchase totals =	$954.47		$1,019.6325	$1,019.63	$1,019.60	$1,019.60