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	$205.88	8.253%	$222.8713	$222.87	$222.85	$222.90
Purchase #2	$24.31	6.502%	$25.8906	$25.89	$25.90	$25.90
Purchase #3	$217.88	12.835%	$245.8449	$245.84	$245.85	$245.80
Purchase #4	$137.34	7.233%	$147.2738	$147.27	$147.25	$147.30
Purchase #5	$209.53	8.525%	$227.3924	$227.39	$227.40	$227.40
Purchase #6	$47.79	6.169%	$50.7382	$50.74	$50.75	$50.70
Purchase #7	$250.37	8.423%	$271.4587	$271.46	$271.45	$271.50
7 purchase totals =	$1,093.10		$1,191.4699	$1,191.46	$1,191.45	$1,191.50