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	$82.69	11.330%	$92.0588	$92.06	$92.05	$92.10
Purchase #2	$182.55	9.630%	$200.1296	$200.13	$200.15	$200.10
Purchase #3	$95.40	6.338%	$101.4465	$101.45	$101.45	$101.40
Purchase #4	$109.83	4.809%	$115.1117	$115.11	$115.10	$115.10
Purchase #5	$228.30	13.802%	$259.81	$259.81	$259.80	$259.80
Purchase #6	$167.40	13.356%	$189.7579	$189.76	$189.75	$189.80
Purchase #7	$99.69	5.800%	$105.472	$105.47	$105.45	$105.50
7 purchase totals =	$965.86		$1,063.7865	$1,063.79	$1,063.75	$1,063.80