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	$42.46	8.215%	$45.9481	$45.95	$45.95	$45.90
Purchase #2	$52.61	4.688%	$55.0764	$55.08	$55.10	$55.10
Purchase #3	$87.51	5.430%	$92.2618	$92.26	$92.25	$92.30
Purchase #4	$169.62	9.842%	$186.314	$186.31	$186.30	$186.30
Purchase #5	$57.96	5.839%	$61.3443	$61.34	$61.35	$61.30
Purchase #6	$191.91	9.755%	$210.6308	$210.63	$210.65	$210.60
Purchase #7	$92.34	4.622%	$96.608	$96.61	$96.60	$96.60
7 purchase totals =	$694.41		$748.1834	$748.18	$748.20	$748.10