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	$226.25	5.341%	$238.334	$238.33	$238.35	$238.30
Purchase #2	$144.36	6.191%	$153.2973	$153.30	$153.30	$153.30
Purchase #3	$165.97	10.776%	$183.8549	$183.85	$183.85	$183.90
Purchase #4	$43.33	5.730%	$45.8128	$45.81	$45.80	$45.80
Purchase #5	$6.55	12.420%	$7.3635	$7.36	$7.35	$7.40
Purchase #6	$201.30	13.215%	$227.9018	$227.90	$227.90	$227.90
Purchase #7	$185.55	11.195%	$206.3223	$206.32	$206.30	$206.30
7 purchase totals =	$973.31		$1,062.8866	$1,062.87	$1,062.85	$1,062.90