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	$234.34	6.730%	$250.1111	$250.11	$250.10	$250.10
Purchase #2	$11.34	12.723%	$12.7828	$12.78	$12.80	$12.80
Purchase #3	$156.53	7.260%	$167.8941	$167.89	$167.90	$167.90
Purchase #4	$23.33	8.726%	$25.3658	$25.37	$25.35	$25.40
Purchase #5	$161.85	13.520%	$183.7321	$183.73	$183.75	$183.70
Purchase #6	$196.78	13.614%	$223.5696	$223.57	$223.55	$223.60
Purchase #7	$148.65	6.790%	$158.7433	$158.74	$158.75	$158.70
7 purchase totals =	$932.82		$1,022.1988	$1,022.19	$1,022.20	$1,022.20