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	$211.30	5.289%	$222.4757	$222.48	$222.50	$222.50
Purchase #2	$221.97	10.448%	$245.1614	$245.16	$245.15	$245.20
Purchase #3	$152.59	6.429%	$162.4	$162.40	$162.40	$162.40
Purchase #4	$67.44	13.442%	$76.5053	$76.51	$76.50	$76.50
Purchase #5	$192.77	12.174%	$216.2378	$216.24	$216.25	$216.20
Purchase #6	$43.39	5.548%	$45.7973	$45.80	$45.80	$45.80
Purchase #7	$187.44	3.282%	$193.5918	$193.59	$193.60	$193.60
7 purchase totals =	$1,076.90		$1,162.1693	$1,162.18	$1,162.20	$1,162.20