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	$214.25	10.817%	$237.4254	$237.43	$237.45	$237.40
Purchase #2	$155.51	10.557%	$171.9272	$171.93	$171.95	$171.90
Purchase #3	$25.35	12.567%	$28.5357	$28.54	$28.55	$28.50
Purchase #4	$99.27	12.666%	$111.8435	$111.84	$111.85	$111.80
Purchase #5	$84.73	13.248%	$95.955	$95.96	$95.95	$96.00
Purchase #6	$181.45	4.411%	$189.4538	$189.45	$189.45	$189.50
Purchase #7	$201.44	13.209%	$228.0482	$228.05	$228.05	$228.00
7 purchase totals =	$962.00		$1,063.1888	$1,063.20	$1,063.25	$1,063.10