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	$189.84	11.312%	$211.3147	$211.31	$211.30	$211.30
Purchase #2	$103.89	5.200%	$109.2923	$109.29	$109.30	$109.30
Purchase #3	$38.80	12.256%	$43.5553	$43.56	$43.55	$43.60
Purchase #4	$196.45	12.321%	$220.6546	$220.65	$220.65	$220.70
Purchase #5	$206.66	6.731%	$220.5703	$220.57	$220.55	$220.60
Purchase #6	$136.42	11.115%	$151.5831	$151.58	$151.60	$151.60
Purchase #7	$64.88	5.231%	$68.2739	$68.27	$68.25	$68.30
7 purchase totals =	$936.94		$1,025.2442	$1,025.23	$1,025.20	$1,025.40