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	$203.95	9.497%	$223.3191	$223.32	$223.30	$223.30
Purchase #2	$25.31	5.168%	$26.618	$26.62	$26.60	$26.60
Purchase #3	$236.78	3.820%	$245.825	$245.83	$245.85	$245.80
Purchase #4	$151.35	3.223%	$156.228	$156.23	$156.25	$156.20
Purchase #5	$106.77	4.687%	$111.7743	$111.77	$111.75	$111.80
Purchase #6	$149.69	8.524%	$162.4496	$162.45	$162.45	$162.40
Purchase #7	$157.76	10.833%	$174.8501	$174.85	$174.85	$174.90
7 purchase totals =	$1,031.61		$1,101.0641	$1,101.07	$1,101.05	$1,101.00