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	$154.63	5.352%	$162.9058	$162.91	$162.90	$162.90
Purchase #2	$165.69	12.127%	$185.7832	$185.78	$185.80	$185.80
Purchase #3	$62.41	6.599%	$66.5284	$66.53	$66.55	$66.50
Purchase #4	$99.39	11.457%	$110.7771	$110.78	$110.80	$110.80
Purchase #5	$226.34	4.515%	$236.5593	$236.56	$236.55	$236.60
Purchase #6	$109.86	3.440%	$113.6392	$113.64	$113.65	$113.60
Purchase #7	$127.37	6.241%	$135.3192	$135.32	$135.30	$135.30
7 purchase totals =	$945.69		$1,011.5122	$1,011.52	$1,011.55	$1,011.50