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	$41.86	3.499%	$43.3247	$43.32	$43.30	$43.30
Purchase #2	$204.68	8.732%	$222.5527	$222.55	$222.55	$222.60
Purchase #3	$76.26	7.856%	$82.251	$82.25	$82.25	$82.30
Purchase #4	$224.27	10.782%	$248.4508	$248.45	$248.45	$248.50
Purchase #5	$124.32	4.467%	$129.8734	$129.87	$129.85	$129.90
Purchase #6	$224.90	6.242%	$238.9383	$238.94	$238.95	$238.90
Purchase #7	$72.96	13.118%	$82.5309	$82.53	$82.55	$82.50
7 purchase totals =	$969.25		$1,047.9218	$1,047.91	$1,047.90	$1,048.00