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	$208.46	12.127%	$233.7399	$233.74	$233.75	$233.70
Purchase #2	$37.33	11.616%	$41.6663	$41.67	$41.65	$41.70
Purchase #3	$58.57	7.310%	$62.8515	$62.85	$62.85	$62.90
Purchase #4	$196.42	10.222%	$216.4981	$216.50	$216.50	$216.50
Purchase #5	$167.88	12.667%	$189.1454	$189.15	$189.15	$189.10
Purchase #6	$102.28	9.666%	$112.1664	$112.17	$112.15	$112.20
Purchase #7	$188.96	8.219%	$204.4906	$204.49	$204.50	$204.50
7 purchase totals =	$959.90		$1,060.5582	$1,060.57	$1,060.55	$1,060.60