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	$51.59	4.459%	$53.8904	$53.89	$53.90	$53.90
Purchase #2	$219.61	10.415%	$242.4824	$242.48	$242.50	$242.50
Purchase #3	$247.52	13.651%	$281.309	$281.31	$281.30	$281.30
Purchase #4	$63.92	6.647%	$68.1688	$68.17	$68.15	$68.20
Purchase #5	$70.26	11.639%	$78.4376	$78.44	$78.45	$78.40
Purchase #6	$189.93	7.664%	$204.4862	$204.49	$204.50	$204.50
Purchase #7	$181.62	3.384%	$187.766	$187.77	$187.75	$187.80
7 purchase totals =	$1,024.45		$1,116.5404	$1,116.55	$1,116.55	$1,116.60