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	$113.39	10.191%	$124.9456	$124.95	$124.95	$124.90
Purchase #2	$199.34	13.155%	$225.5632	$225.56	$225.55	$225.60
Purchase #3	$162.54	7.859%	$175.314	$175.31	$175.30	$175.30
Purchase #4	$233.37	8.376%	$252.9171	$252.92	$252.90	$252.90
Purchase #5	$62.63	6.816%	$66.8989	$66.90	$66.90	$66.90
Purchase #6	$69.32	13.138%	$78.4273	$78.43	$78.45	$78.40
Purchase #7	$123.74	8.435%	$134.1775	$134.18	$134.20	$134.20
7 purchase totals =	$964.33		$1,058.2436	$1,058.25	$1,058.25	$1,058.20