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	$191.46	13.195%	$216.7231	$216.72	$216.70	$216.70
Purchase #2	$28.61	11.110%	$31.7886	$31.79	$31.80	$31.80
Purchase #3	$28.74	13.751%	$32.692	$32.69	$32.70	$32.70
Purchase #4	$222.60	11.871%	$249.0248	$249.02	$249.00	$249.00
Purchase #5	$50.46	5.341%	$53.1551	$53.16	$53.15	$53.20
Purchase #6	$201.72	8.858%	$219.5884	$219.59	$219.60	$219.60
Purchase #7	$233.51	10.671%	$258.4279	$258.43	$258.45	$258.40
7 purchase totals =	$957.10		$1,061.3999	$1,061.40	$1,061.40	$1,061.40