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	$204.48	3.460%	$211.555	$211.56	$211.55	$211.60
Purchase #2	$60.56	11.265%	$67.3821	$67.38	$67.40	$67.40
Purchase #3	$219.42	5.113%	$230.6389	$230.64	$230.65	$230.60
Purchase #4	$27.38	4.618%	$28.6444	$28.64	$28.65	$28.60
Purchase #5	$162.90	5.757%	$172.2782	$172.28	$172.30	$172.30
Purchase #6	$227.99	4.496%	$238.2404	$238.24	$238.25	$238.20
Purchase #7	$18.61	12.286%	$20.8964	$20.90	$20.90	$20.90
7 purchase totals =	$921.34		$969.6354	$969.64	$969.70	$969.60