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	$111.55	5.314%	$117.4778	$117.48	$117.50	$117.50
Purchase #2	$172.95	5.668%	$182.7528	$182.75	$182.75	$182.80
Purchase #3	$86.89	8.552%	$94.3208	$94.32	$94.30	$94.30
Purchase #4	$148.44	13.405%	$168.3384	$168.34	$168.35	$168.30
Purchase #5	$107.92	4.165%	$112.4149	$112.41	$112.40	$112.40
Purchase #6	$204.80	7.623%	$220.4119	$220.41	$220.40	$220.40
Purchase #7	$151.31	11.398%	$168.5563	$168.56	$168.55	$168.60
7 purchase totals =	$983.86		$1,064.2729	$1,064.27	$1,064.25	$1,064.30