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	$182.36	6.688%	$194.5562	$194.56	$194.55	$194.60
Purchase #2	$187.42	4.507%	$195.867	$195.87	$195.85	$195.90
Purchase #3	$171.73	8.165%	$185.7518	$185.75	$185.75	$185.80
Purchase #4	$134.46	11.779%	$150.298	$150.30	$150.30	$150.30
Purchase #5	$168.89	10.689%	$186.9427	$186.94	$186.95	$186.90
Purchase #6	$54.61	9.385%	$59.7351	$59.74	$59.75	$59.70
Purchase #7	$42.86	13.748%	$48.7524	$48.75	$48.75	$48.80
7 purchase totals =	$942.33		$1,021.9032	$1,021.91	$1,021.90	$1,022.00