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	$89.67	7.228%	$96.1513	$96.15	$96.15	$96.20
Purchase #2	$222.90	10.255%	$245.7584	$245.76	$245.75	$245.80
Purchase #3	$81.61	11.584%	$91.0637	$91.06	$91.05	$91.10
Purchase #4	$89.59	13.489%	$101.6748	$101.67	$101.65	$101.70
Purchase #5	$185.46	13.717%	$210.8995	$210.90	$210.90	$210.90
Purchase #6	$47.82	11.608%	$53.3709	$53.37	$53.35	$53.40
Purchase #7	$195.77	8.818%	$213.033	$213.03	$213.05	$213.00
7 purchase totals =	$912.82		$1,011.9516	$1,011.94	$1,011.90	$1,012.10