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	$241.75	8.723%	$262.8379	$262.84	$262.85	$262.80
Purchase #2	$65.36	3.592%	$67.7077	$67.71	$67.70	$67.70
Purchase #3	$81.63	13.744%	$92.8492	$92.85	$92.85	$92.80
Purchase #4	$65.95	8.388%	$71.4819	$71.48	$71.50	$71.50
Purchase #5	$45.27	6.746%	$48.3239	$48.32	$48.30	$48.30
Purchase #6	$155.75	6.292%	$165.5498	$165.55	$165.55	$165.50
Purchase #7	$223.59	9.850%	$245.6136	$245.61	$245.60	$245.60
7 purchase totals =	$879.30		$954.3640	$954.36	$954.35	$954.20