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	$82.29	12.744%	$92.777	$92.78	$92.80	$92.80
Purchase #2	$96.88	3.129%	$99.9114	$99.91	$99.90	$99.90
Purchase #3	$194.49	7.320%	$208.7267	$208.73	$208.75	$208.70
Purchase #4	$17.27	6.237%	$18.3471	$18.35	$18.35	$18.30
Purchase #5	$155.53	6.435%	$165.5384	$165.54	$165.55	$165.50
Purchase #6	$191.46	9.512%	$209.6717	$209.67	$209.65	$209.70
Purchase #7	$191.98	13.768%	$218.4118	$218.41	$218.40	$218.40
7 purchase totals =	$929.90		$1,013.3841	$1,013.39	$1,013.40	$1,013.30