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	$233.63	4.638%	$244.4658	$244.47	$244.45	$244.50
Purchase #2	$218.40	4.576%	$228.394	$228.39	$228.40	$228.40
Purchase #3	$40.78	11.234%	$45.3612	$45.36	$45.35	$45.40
Purchase #4	$96.38	13.497%	$109.3884	$109.39	$109.40	$109.40
Purchase #5	$57.33	8.176%	$62.0173	$62.02	$62.00	$62.00
Purchase #6	$60.91	7.239%	$65.3193	$65.32	$65.30	$65.30
Purchase #7	$159.63	7.445%	$171.5145	$171.51	$171.50	$171.50
7 purchase totals =	$867.06		$926.4605	$926.46	$926.40	$926.50