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	$182.87	7.251%	$196.1299	$196.13	$196.15	$196.10
Purchase #2	$172.85	11.421%	$192.5912	$192.59	$192.60	$192.60
Purchase #3	$128.57	10.372%	$141.9053	$141.91	$141.90	$141.90
Purchase #4	$27.87	13.419%	$31.6099	$31.61	$31.60	$31.60
Purchase #5	$209.97	12.819%	$236.8861	$236.89	$236.90	$236.90
Purchase #6	$245.34	11.773%	$274.2239	$274.22	$274.20	$274.20
Purchase #7	$10.34	10.206%	$11.3953	$11.40	$11.40	$11.40
7 purchase totals =	$977.81		$1,084.7416	$1,084.75	$1,084.75	$1,084.70