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	$219.73	3.838%	$228.1632	$228.16	$228.15	$228.20
Purchase #2	$222.33	6.199%	$236.1122	$236.11	$236.10	$236.10
Purchase #3	$55.86	5.858%	$59.1323	$59.13	$59.15	$59.10
Purchase #4	$124.49	13.124%	$140.8281	$140.83	$140.85	$140.80
Purchase #5	$150.81	12.268%	$169.3114	$169.31	$169.30	$169.30
Purchase #6	$63.91	3.679%	$66.2612	$66.26	$66.25	$66.30
Purchase #7	$132.82	11.754%	$148.4317	$148.43	$148.45	$148.40
7 purchase totals =	$969.95		$1,048.2401	$1,048.23	$1,048.25	$1,048.20