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	$78.26	5.671%	$82.6981	$82.70	$82.70	$82.70
Purchase #2	$217.46	7.554%	$233.8869	$233.89	$233.90	$233.90
Purchase #3	$152.96	13.828%	$174.1113	$174.11	$174.10	$174.10
Purchase #4	$234.81	11.609%	$262.0691	$262.07	$262.05	$262.10
Purchase #5	$99.89	3.435%	$103.3212	$103.32	$103.30	$103.30
Purchase #6	$124.72	4.290%	$130.0705	$130.07	$130.05	$130.10
Purchase #7	$156.36	4.168%	$162.8771	$162.88	$162.90	$162.90
7 purchase totals =	$1,064.46		$1,149.0342	$1,149.04	$1,149.00	$1,149.10